wp3_p7_WidexLoginPortlet_168
w3p7_User Nav - Web Content Viewer (JSR 286)
WidexProResearchArticles
Widget top left
Small Text Large Text Text Size
Print Bookmark and Share
Widget top right
University Library
Search University Library by Topic
BEYOND
GOING BEYOND –A Testament of Progressive Innovation
As we learn more about aging, cognition, and the importance of hearing, it is becoming clear that one goal of hearing aid design and fitting should be to create a favorable signal-to-noise ratio and reduce the amount of effort required to decode speech. In short, we need to facilitate communication by making speech signals more accessible to the listener –or what Widex calls Effortless Hearing.
Wireless Streaming: Sound Quality Comparison Among MFi Hearing Aids
The ability to stream from an iPhone to hearing aids using the 2.4 GHz band is becoming popular, and many hearing aid manufacturers carry products in their portfolio with this functionality. Direct streaming provides easy access to phone calls and media content without having to use an intermediary device in the signal chain.
Signal Processing – U Platform
UNIQUE Solutions for First Time Hearing Aid Wearers
The MarkeTrak VIII (2009) report on 25-year trends in the hearing aid industry revealed that only 1 in 4 people with a hearing loss wear hearing aids. Among those with a hearing impairment, only 1 in 10 with a mild hearing loss wears hearing aids, whereas 4 in 10 with a moderate-to-severe hearing loss wear hearing aids. These numbers show that those in the mild hearing loss category do not wear hearing aids as readily as those with more significant hearing loss. Looking at this from a different perspective, it suggests that there is still a market of potential hearing aid wearers that the hearing care professionals can tap into: those with a mild hearing loss.
New Technology for Effortless Hearing: A “Unique” Perspective
The UNIQUE, a new hearing aid from Widex, is designed to provide effortless hearing by addressing the nuances hearing aids need to capture and process for patients’ unique, individualized listening needs.
Efficiency of a Wind Noise Attenuation Algorithm
As wind noise has become a major concern with BTE intruments, continued effort has targeted advancing wind-noise reduction algorithms. This paper reports on the effectiveness of the widex Unique wind noise attenuation (WNA) algorithm.
Widex Fitting Rationale: A Need for a Change?

This article examines Widex’s fitting rationale and method in the field and in the laboratory using UNIQUE hearing aids.

Signal Processing – True ISP
Designing Hearing Aid Technology to Support Benefits in Demanding Situations, Part 1

Part 1 of a study that explains why the A/D converter has been the “Achilles heel” in hearing aid design and how the Dream True ISP technology addresses this.

Designing Hearing Aid Technology to Support Benefits in Demanding Situations, Part 2

Part 2 of a study that discusses the benefits of Dream True ISP technology in demanding situations and the improvements demonstrated in speech perception in loud noise.

What is Good Hearing Aid Sound Quality, and Does it Really Matter?

The authors discuss the design requirements for natural sound reproduction in a hearing aid.

Signal Processing - DSP & ISP
Technical Improvements to Enhance the Performance of CIC Instruments.

The author discussed how the performance of a CIC hearing aid could be improved through the use of DSP techniques. The hope is that more people with mild to severe degrees of hearing loss would wear hearing aids.

Amplification Rationale of a DSP Hearing Instrument.

The author provided a description of the audiological rationale for the different algorithms used in the Senso C-series hearing aids. Specifically, the rationale for the following two key algorithms was discussed:

  • Recruitment and loudness mapping
  • Speech understanding in noise and speech enhancement algorithm
Open or Closed? Let’s Weigh the Difference.

The author discussed why it is unreasonable to label present-day digital hearing aids as “open” and why the Senso hearing aid should be labeled as a “dedicated” system and not a “closed” system

Digital Signal Processing: Benefits and Expectations.

The authors discussed the various benefits that can be realized with digital signal processing techniques including better strategies to map loudness, feedback control, speech detection in noise etc. The authors expect other manufacturers to develop 100% truly digital hearing aids in the coming years, and that more “intelligent” hearing aids using neural network modeling would be available in the future.

New Solutions for Age-Old Hearing Aid Problems.

In this article the author provided a summary of the consequences of a sensorineural hearing loss and a review of all the features in the new Diva hearing aids. Such features include the 15-channel enhanced dynamic range compression (EDRC), noise reduction, directional microphone (Locator), active feedback cancellation, occlusion manager, and the music program.

Ensuring High-Fidelity in Hearing Aid Sound Processing.

High-fidelity processing in hearing aids requires careful considerations of each step of the signal pathway and using signal processing algorithms to preserve the natural spectral-temporal content of the input. This paper offers a perspective and summary on the considerations that affect the faithfulness in which a hearing aid reproduces sounds while compensating for the hearing loss of the wearer. Components and processes designed to help preserve the natural spectral-temporal content discussed include: the microphone, analog-to-digital conversion, sampling frequency, quantization, slow acting WDRC, receiver bandwidth, and output limiting. These considerations are included in the design of the new Widex Mind hearing aid, whose TruSound algorithm is designed to exemplify these considerations.

Digital Wireless Hearing Aids, Part 1: A Primer

Taking an audio signal and transmitting/receiving it digitally is a multi-stage process, with each step influencing the quality of the transmitted sounds. This article provides a primer about the steps involved in the process for both near- and far-field transmission of signals.

Comparing the Performance of the Widex Senso with Analog Hearing Aids.

Speech recognition scores were determined with the Senso hearing aids (C8 & CX) and subjects’ (N=50) own hearing aids (3/4 are 2-channel WDRC devices) on the SPIN test at 50, 65, and 80 dB SPL (SNR =+8). In addition, the SNR required to achieve 50% correct score on the HINT was also determined for both hearing aids. The APHAB and the Washington University questionnaire were administered at the end of a 30-day trial to evaluate subjective preference.

Using Digital Signal Processing to Enhance the Performance of Dual Microphones.

In this article the authors reviewed the wearers’ expectations for a directional microphone system and provided a description of the design of the Locator microphone system used in the Diva hearing aids (BTE and ITE/ITC). Because of the wearers’ expectations for consistent and guaranteed signal-to-noise ration (SNR) improvement all the time in all environments, automatic and seamless adjustment, no artifacts like an increase in circuit and wind noise, the Diva hearing aids are designed with an OptiMic system that ensures consistent performance over time. In addition, the functions of a Noise Classification Unit, an Adaptive SNR optimizer, and a Beamformer were reviewed.

Using DSP to Screen Hearing Aid Component Problems.

The rationale and mechanism of a Self-Test to screen potential hearing aid component defect in the Diva hearing aid was reported. In addition, the results of a validation study on the Self-Test were reported. Using in-house technicians as the benchmark, 200 custom Diva hearing aids that were sent in for repair were tested with the Self-Test and then by in-house technicians for typical evaluation. The results showed that the Self-Test has a high hit rate in that 87.5% of the custom products were correctly identified by the Self-Test. Indeed, when the Self-Test consistently indicated a problem, a problem is always identified by the technicians. The proper ways to use the self-test and interpret the results were discussed.

Integrated Signal Processing – A New Standard in Hearing Aid Processing.

This supplement included a series of articles that described the key features on the Inteo hearing aid. Specifically, it included a chapter on the rationale for Integrated Signal Processing (ISP); a chapter on the High Definition Sound Analysis; a chapter on the rationale for the Assessment of In-situ Acoustics (AISA); a chapter on the Noise Management strategies used in the Inteo; a chapter on the HD Locator; a chapter on the MD-Active feedback cancellation, and a chapter on the Audibility Extender – the linear frequency transposition algorithm used in the Inteo.

Compression
Fitting a Wide Range Compression Hearing Instrument Using Real-Ear Threshold Data: A New Strategy.

The authors reviewed the sources of variability that could affect the accuracy of loudness growth measurements. These include: stimulus uncertainties (as it is measured in the earcanal); methodological differences (of measuring “loudness”) and the problem in specifying the input-output curve (loudness summation not included). The description and justification of the in-situ sensogram method was provided.

Rationale and Requirements for a Slow-Acting Compression Hearing Aid.

The author explained how short attack and release times on a compression hearing aid could result in temporal-intensity distortion. In addition, the effect of lengthening the release time to minimize temporal distortion was also illustrated. The author provided arguments for using a long release time (thus slow acting WDRC) in compression hearing aids, and discussed the technical considerations crucial to designing an effective slow acting compression hearing aid.

Optimizing Compression: Advantages of Low Compression Threshold.

The author listed the difficulties in achieving a low compression threshold in wide dynamic range compression (WDRC) hearing aids and explained how DSP allows one to achieve an “optimal” CT in today’s hearing aids.

MPO: A Forgotten Parameter in Hearing Aid Fitting.

This paper discussed the importance of selecting a hearing aid with a sufficiently high Maximum Power Output (MPO) so that the output of the hearing aid would not be unnecessarily limited to a level below the wearer’s acceptable loudness level or suffer a poorer signal-to-noise ratio (SNR) or both. A theoretical rationale for that speculation, as well as waveforms showing the audio recordings of hearing aids with different levels of MPO were provided for demonstration.

Ensuring High-Fidelity in Hearing Aid Sound Processing.

High-fidelity processing in hearing aids requires careful considerations of each step of the signal pathway and using signal processing algorithms to preserve the natural spectral-temporal content of the input. This paper offers a perspective and summary on the considerations that affect the faithfulness in which a hearing aid reproduces sounds while compensating for the hearing loss of the wearer. Components and processes designed to help preserve the natural spectral-temporal content discussed include: the microphone, analog-to-digital conversion, sampling frequency, quantization, slow acting WDRC, receiver bandwidth, and output limiting. These considerations are included in the design of the new Widex Mind hearing aid, whose TruSound algorithm is designed to exemplify these considerations.

Microphone (and Directional) Research
The Advantage of a Low Compression Threshold in Directional Microphones.

The speech recognition ability of thirty subjects was compared between the Senso directional hearing aid and a programmable dual-mic hearing aid in its two signal processing modes (linear and WDRC) and microphone modes (omnidirectional and directional). Sentence materials from the SPIN test were presented at 50 dB SPL and 65 dB SPL from the back (1800) in quiet for all five hearing aid conditions. In addition, speech recognition scores of the hearing aids in the directional mode were also determined with the typical speech front, noise back presentation (SNR=-5).

Digital Versus Analog Signal Processing: Effect of Directional Microphone.

Speech recognition scores were determined with the Senso C9 directional hearing aid, the C8 omnidirectional hearing aid, and subjects’ (N=40) own omnidirectional hearing aids using the Speech Perception In Noise (SPIN) test in the typical speech front and noise back (1800 ) configuration. Noise levels were set at 65 dB SPL and 75 dB SPL, and speech levels were set to yield a SNR of +7, 0, and –7. The obtained speech recognition scores were extrapolated to yield an estimated signal-to-noise ratio improvement of the C8 and the C9 hearing aids. Subjects also wore the C9 home for a month and indicated their preference between the C9 and their own hearing aids in a variety of listening environments on the Washington University questionnaire.

Use of a Digital Hearing Aid with Directional Microphones in School-Aged Children.

The authors reported on a clinical study with 20 hearing-impaired children between 8 and 12 years of age in the Portland School District. Nine of the children had a mild-to-moderate degree of hearing loss and eleven had a moderate-to-severe degree of hearing loss. Subjects were fit with the C9 (for the mild loss) and the C19 (for the moderate/ severe loss) directional SENSO hearing aids. Subjects wore the aids for over 30 days and were tested on the W-22 word list at 65 dB SPL in three SNR of +7, 0, and –7 dB (speech front and noise back condition), the LIFE questionnaire, as well as a parent questionnaire.

Design Considerations in Directional Microphones.

In this article, the authors offered their perspectives on the design of hearing aids with directional microphones. Specifically, the authors discussed the factors that affect the performance of a directional microphone, including port separation and delay value. In addition, the differences between a dedicated directional microphone and a dual microphone system – the issue of the need for microphone matching (sensitivity and phase), potential performance difference, and the limitations from circuit noise, wind noise, and reduced sensitivity from sides and back of a directional microphone are discussed. It was concluded that a dual microphone system and a dedicated system have the same the same potential to improve the signal-to-noise ratio of the listening environment, and both are subject to the same limiting factors.

Preserving Directional Benefits for New Users Wearing Smaller Hearing Aids.

In this article, the authors speculated that if a large vent would minimize the noted directional advantage of a directional hearing aid, the Occlusion Management feature on the Diva hearing aid could minimize the requirement for a large vent while maintaining wearer satisfaction to his/her own voice. Thus, the authors examined the improvement in speech scores in 7 experienced (thresholds below 500 Hz exceeds 40 dB HL) and 7 new hearing aid wearers (thresholds below 500 Hz below 20 dB HL) between the Locator mic and the omnidirectional mic on the Diva hearing aid. The average vent diameter was 0.5 mm for the experienced subjects and 2 mm for the new wearers. A Widex party noise was placed at 900, 1800, and 2700 with speech presented in front. On the HINT, an average improvement of 6 dB SNR was noted for the experienced subjects and 4 dB was noted for the new hearing aid wearers. As much as 35% improvement in speech recognition score was noted on the SPIN for both groups of wearers, although the SNR test condition at which this occurred differed between the two groups of subjects.

Is Real-World Directional Benefit Predictable?

This paper described the results of a study in which hearing impaired individuals of all configurations of hearing loss (and degrees) were fitted with the directional Diva hearing aid (some ITE, ITC, and BTE) with the appropriate size vent (from 3 mm to no vent, depending on the degree of loss at 500 Hz). The amount of directional benefit (defined as the difference in SNR between an omnidirectional microphone and the directional microphone) obtained with the HINT test with the noise sources from the sides and back were measured and correlated with various demographic variables. The results showed that directional benefit increased as the amount of hearing loss increased with those with minimal hearing loss receiving at least 1-2 dB of benefit. It was speculated that the vent size (which was dispensed based on the degree of hearing loss at 500 Hz) and the additional processing, such as noise reduction affected the outcome of the study.

Timing is (Almost) Everything – Fully Adaptive Directional Microphone.

This article demonstrates the importance of stimulus duration in the verification of an adaptive directional microphone using two of the most popular verification systems – Audioscan Verifit and Frye 6500 test systems. Timing is important because a fully adaptive directional microphone takes time to switch from an omnidirectional microphone to various polar patterns. A stimulus that is too brief in duration may not fully activate the directional mic and may result in only partial effectiveness. The implication of the demonstration is that, at least for the Diva, one must use a continuous noise that is longer than 10 s in order to fully activate the directional microphone for verification (such as measuring front-to-back ratio) and validation (such as SNR using HINT or quickSIN) measures. In addition, the signal level must be higher than 55 dB SPL to activate the directional mode.

Preserving Audibility in Directional Microphones: Implications for Adults and Children.

This article summarizes the findings from two pivotal studies on the directional benefits provided by the Diva Locator microphone. The first study from Valente and Mispagel (2004) showed the significant SNR benefit (4-6 dB) provided by the Diva locator in noise. The second study from Kuk et al (2005) showed the audibility preservation of the Locator microphone in quiet environments. These studies showed that if one wants to preserve audibility in quiet while maximizing noise reduction, the design rationale used in the Diva Locator should be considered. The implication of these studies is that one may need to reconsider children’s candidacy for a directional hearing aid.

Subjective and Objective Evaluation of Noise Management Algorithms.

This study measured the subjective and objective improvement of speech intelligibility in noise offered by the Widex Inteo hearing aid that uses a fully adaptive directional microphone and a noise reduction algorithm that optimizes the Speech Intelligibility Index (SII). The efficacy of two noise management algorithms was compared using the Acceptable Noise Level (ANL, subjective measure) and HINT (objective measure) in order to determine if each algorithm could improve speech recognition in noise. The results showed a significant improvement in SNR for both features when measured subjectively and objectively. Specifically, on the HINT, the average participant showed a SNR improvement of 4.0 dB with the directional microphones, 2.5 dB with the SE, and 4.6 dB with “dir+SE” when compared to the “omni” microphone condition. On the subjective ANL, the average participant showed a SNR improvement of 2.8 dB with the directional microphones, 3.3 dB with the SE, and 5.7 dB with “dir+SE” over the “omni” microphone condition. Furthermore, a moderate correlation exists (r=0.46 to 0.73) between the subjective and objective benefits with the directional microphone and the directional microphone with SE. The results suggest that the directional microphone and the SII-based noise reduction algorithm may improve the SNR of the listening environments and both the HINT and the ANL may be used to study their benefit.

Using Digital Signal Processing to Enhance the Performance of Dual Microphones.

In this article the authors reviewed the wearers’ expectations for a directional microphone system and provided a description of the design of the Locator microphone system used in the Diva hearing aids (BTE and ITE/ITC). Because of the wearers’ expectations for consistent and guaranteed signal-to-noise ration (SNR) improvement all the time in all environments, automatic and seamless adjustment, no artifacts like an increase in circuit and wind noise, the Diva hearing aids are designed with an OptiMic system that ensures consistent performance over time. In addition, the functions of a Noise Classification Unit, an Adaptive SNR optimizer, and a Beamformer were reviewed.

Performance of an Automatic Adaptive Dual-Microphone ITC Digital Hearing Aid.

This article described the clinical evaluation conducted at Washington University on the SNR efficacy of the Diva ITC hearing aids in 20 hearing impaired individuals. Subjects were tested with the HINT sentences with noise presented from directly behind, to the sides, and to the sides and back. All subjects reported an improvement in SNR with the locator microphone over the omnidirectional microphone. The amount of improvement also varied with the noise azimuth. An average of 6 dB improvement was seen when the noise source was at an 1800. The improvement was around 4 dB when the noise sources were to the sides and back. This magnitude of improvement was the highest reported for a two-mic directional custom product.

Performance of a Fully Adaptive Directional Microphone to Signals Presented from Various Azimuths.

This article reports on the study to examine the ability of the Diva Locator to preserve the audibility of sounds presented from different azimuths and at different input levels of 50, 65, and 80 dB SPL. Hearing impaired subjects were tested monaurally (right only) with the Diva hearing aid in three modes – omnidirectional, fixed directional, and fully adaptive mode. Aided sound-field thresholds were determined as well as speech recognition in quiet using the CASPA test at three input levels. Stimuli were presented at 00, 450, 900, 1350, and 1800 with the non-test ear occluded. The results showed that the aided thresholds obtained with the adaptive mic were similar to the omnidirectional mic, and poorest with the fixed directional mic. The worst thresholds were obtained at the null of the polar pattern (1350). Speech recognition in quiet showed similar pattern, with recognition score for the fixed directional mic at 1350 at a 50 dB SPL input level over 50% poorer than the omni mic and adaptive mic conditions. The results showed that a fixed directional microphone has a definite limitation on the recognition of soft sounds presented at its null. It further showed that the fully adaptive Locator mic functioned liked an omnidirectional microphone in quiet. The audibility limitation of a fixed directional microphone is most significant at a low input level.

Speech & Language of Children Using Hearing Aids with Adaptive Directional & Noise Reduction Features.

This paper reviews longitudinal speech-language outcomes of a group of school age children using hearing aid noise reduction and adaptive directional features. These results, obtained through collaboration between school audiologist and speech-language pathologist, reveal that receptive and expressive language scores are stable or improved over a three-year period of use.

Speech in Noise Performance of a Micro-Size BTE.

This article describes the reasons why the directional microphone performance on a micro-size hearing aid may not be assumed because of the constraints on microphone placement. This lowers the directivity index of the hearing aid, and if not considered, could lower the SNR effectiveness of the hearing aid. In order to ensure that the m-model hearing aid is effective in noise, we tested 19 subjects with various degrees and configurations of hearing loss with the IN-9 and IN-m micro-size hearing aid with open-ear fittings and occluded fittings. There was no difference in SNR performance between the IN-9 and IN-m hearing aids. Furthermore, as much as 8 dB of SNR improvement was observed with the IN-m configured with the directional microphone and speech enhancer over the omnidirectional microphone mode. In an open-ear fitting, as much as 4 dB SNR improvement was observed. Post-microphone processing was attributed to the observations.

Efficacy of an Adaptive Directional Microphone and a Noise Reduction System for School-Aged Children.

A non-randomized, experimental study utilizing double-blinding was implemented to investigate differences in word recognition performance of school-aged children utilizing adaptive directional microphone and noise reduction (NR) features. Children from two educational facilities participated in this study. Signal-to-noise-ratio (SNR) benefit of the adaptive directional system was estimated to be 7.6 dB. No SNR benefit was measured for the NR feature; however no decrease in performance was observed either. Subjective difficulty for desired sounds originating from various azimuths was not significantly greater in either the adaptive directional or NR modes. Results indicate that for the purposes of improving SNR, adaptive directional microphone systems, but not NR systems, are potentially efficacious hearing aid (HA) fitting options for school-aged children.

Feedback Cancellation
Understanding Feedback and Digital Feedback Cancellation Strategies.

In this article the authors used Control theory to provide a brief quantitative explanation for acoustic feedback, citing the frequency characteristics of the feedback path and the gain on the hearing aid as the two main factors for feedback. In addition, the authors reviewed the three approaches (preventive, acoustic, and the electronic) that clinicians used to control feedback in hearing aids. An explanation of the difficulty with each approach, including some DSP hearing aids is provided. These difficulties are considered in the design of the Diva Feedback Cancellation system. In the Diva system, two components – a slow-acting component called Feedback Path Simulator (FPS) interacts with a fast component called Dynamic cancellation Optimizer (DCO) to prevent feedback occurrence by increasing available gain as much as 10-12dB.

The Real-World Benefits and Limitations of Active Digital Feedback Cancellation.

This is a follow-up paper to the previous article on the “Understanding Feedback…” by the same authors. However, in this article, the authors reviewed the situations in which an active feedback cancellation system may be beneficial to the hearing aid wearers, and situations in which such a system may not be of any benefits to the wearers. The authors also pointed out that despite the additional available gain provided by such a system, clinicians should not use this mechanism to extend the fitting range of their hearing aids.

Changing with the Times – Additional Criteria to Judge the Effectiveness of Active Feedback Cancellation Algorithm.

This paper is a third paper in a series that described the rationale for active feedback cancellation algorithms in digital hearing aids. In addition to a brief overview, this paper added that the increase in available gain is not the only criterion to evaluate the effectiveness of an active feedback system. The freedom from artifacts or misidentification of feedback, and the responsiveness to changes in the feedback paths are also factors to consider. It also included some efficacy data from the study of the new feedback algorithm used in the Inteo hearing aids.

Noise Reduction & Speech in Noise
Speech Intelligibility Benefits of Hearing Aids at Various Input Levels

Study results show how the Dream technology provides aided speech-in-noise benefit at very high noise inputs in a controlled environment.

Improving Hearing Aid Performance in Noise: Challenges and Strategies.

In this article, the authors discussed the difficulties involved in designing a noise reduction system that is targeted to improve speech understanding in background noise. Specifically, the authors discussed how the criteria for “noise” would affect the efficacy of the algorithm, along with the design variables affecting the specificity of noise identification and noise reduction. The authors also discussed the mechanism of the noise reduction algorithm used in the Diva hearing aid, and offered some perspectives on its potential real-life efficacy.

Noise Management Algorithm May Improve Speech Intelligibility in Noise.

This article compares the differences between a classical noise reduction algorithm and the newest noise management algorithm used in the Inteo - the Speech Enhancer that optimizes the Speech Intelligibility Index (SII) in noise. In short, classical noise reduction algorithms reduce gain on a hearing aid depending on the input level as well as the SNR. They do not consider the degree of hearing loss of the wearers. On the other hand, the Speech Enhancer algorithm considers the degree of hearing loss of the wearer such that for the same stimulus condition, a wearer with more loss will likely experience less gain reduction.

Speech in Noise Performance of a Micro-Size BTE.

This article describes the reasons why the directional microphone performance on a micro-size hearing aid may not be assumed because of the constraints on microphone placement. This lowers the directivity index of the hearing aid, and if not considered, could lower the SNR effectiveness of the hearing aid. In order to ensure that the m-model hearing aid is effective in noise, we tested 19 subjects with various degrees and configurations of hearing loss with the IN-9 and IN-m micro-size hearing aid with open-ear fittings and occluded fittings. There was no difference in SNR performance between the IN-9 and IN-m hearing aids. Furthermore, as much as 8 dB of SNR improvement was observed with the IN-m configured with the directional microphone and speech enhancer over the omnidirectional microphone mode. In an open-ear fitting, as much as 4 dB SNR improvement was observed. Post-microphone processing was attributed to the observations.

Speech Preservation in Noise Management Strategies.

Noise management strategies such as directional microphones and noise reduction algorithms, while improving the SNR, may decrease the audibility of desired signals for some, if not all wearers. In this paper, we discussed what design considerations were made to preserve audibility while enhancing SNR. Specifically, the activation threshold, the time constants are important considerations. Multi-channel capability (in noise reduction and adaptive directionality) would limit the gain reduction to the affected frequencies only and avoid unnecessary gain reduction. The rationale behind the Speech Enhancer that of maximizing the speech intelligibility index (SII) was also described as a way to preserve audibility while improving SNR.

Subjective and Objective Evaluation of Noise Management Algorithms.

This study measured the subjective and objective improvement of speech intelligibility in noise offered by the Widex Inteo hearing aid that uses a fully adaptive directional microphone and a noise reduction algorithm that optimizes the Speech Intelligibility Index (SII). The efficacy of two noise management algorithms was compared using the Acceptable Noise Level (ANL, subjective measure) and HINT (objective measure) in order to determine if each algorithm could improve speech recognition in noise. The results showed a significant improvement in SNR for both features when measured subjectively and objectively. Specifically, on the HINT, the average participant showed a SNR improvement of 4.0 dB with the directional microphones, 2.5 dB with the SE, and 4.6 dB with “dir+SE” when compared to the “omni” microphone condition. On the subjective ANL, the average participant showed a SNR improvement of 2.8 dB with the directional microphones, 3.3 dB with the SE, and 5.7 dB with “dir+SE” over the “omni” microphone condition. Furthermore, a moderate correlation exists (r=0.46 to 0.73) between the subjective and objective benefits with the directional microphone and the directional microphone with SE. The results suggest that the directional microphone and the SII-based noise reduction algorithm may improve the SNR of the listening environments and both the HINT and the ANL may be used to study their benefit.

Speech-in-Noise Potential of Hearing Aids with Extended Bandwidth.

This study shows that a hearing aid with an extended bandwidth may improve the wearer's tolerance for noise in a noisy environment. However, to achieve this improvement, the prescriptive gain target needs to accommodate the added bandwidth of the hearing aid.

Effect of Maximum Power Output and Noise Reduction on Speech Recognition in Noise.

The maximum power output (MPO) of a hearing aid was typically discussed in the context of avoiding loudness discomfort. However, an MPO that is too low, as in the cases to avoid discomfort for people with a severe loudness tolerance problem and hearing losses that exceed the fitting range of the hearing aids, could negatively affect sound quality and speech intelligibility in noise. The current study was designed to demonstrate the degradation in speech intelligibility in noise on the HINT (Hearing in Noise Test) when the MPO of the wearers’ hearing aids was lowered by 10 dB from the default. The interactions with noise reduction (NR) algorithms (classic [NR-classic] and Speech Enhancer [NR-SE]) were also examined.

Efficacy of an Adaptive Directional Microphone and a Noise Reduction System for School-Aged Children.

A non-randomized, experimental study utilizing double-blinding was implemented to investigate differences in word recognition performance of school-aged children utilizing adaptive directional microphone and noise reduction (NR) features. Children from two educational facilities participated in this study. Signal-to-noise-ratio (SNR) benefit of the adaptive directional system was estimated to be 7.6 dB. No SNR benefit was measured for the NR feature; however no decrease in performance was observed either. Subjective difficulty for desired sounds originating from various azimuths was not significantly greater in either the adaptive directional or NR modes. Results indicate that for the purposes of improving SNR, adaptive directional microphone systems, but not NR systems, are potentially efficacious hearing aid (HA) fitting options for school-aged children.

Speech & Language of Children Using Hearing Aids with Adaptive Directional & Noise Reduction Features.

This paper reviews longitudinal speech-language outcomes of a group of school age children using hearing aid noise reduction and adaptive directional features. These results, obtained through collaboration between school audiologist and speech-language pathologist, reveal that receptive and expressive language scores are stable or improved over a three-year period of use.

Linear Frequency Transposition (Audibility Extender)
Linear Frequency Transposition: Extending the Audibility of High Frequency Information.

This paper provided an explanation of frequency lowering techniques and a brief review for what a commercial frequency lowering algorithm must consider in its design. It went on to describe the mechanism behind the newest frequency transposition algorithm used in the Inteo hearing aid – the Audibility Extender, whereby the high frequency sounds are linearly transposed to one octave below a start frequency. Preliminary subjective data on the algorithm on 20 hearing impaired wearers were also reported.

Use of Frequency Transposition in Thin-Tube, Open-Ear Fittings.

This paper reported on the efficacy of using the AE algorithm on high frequency hearing loss patients who wear open-ear fitting hearing aids. The rationale for using this group of patients as well as the results of the intervention was discussed in the paper. In general, this group of patients showed a slight improvement over the master program (less than 5%) when initially fit with the AE program. Improvement increased to 10-15% on average after the patients had worn the AE program for two weeks with directed listening.

Twelve Lessons Learned About Linear Frequency Transposition.

This paper summarized the key findings/lessons we have learned in the last three years of studies with the Audibility Extender (AE) program. The studies included young subjects with normal hearing, and hearing impaired adults and children with various degrees and configurations of hearing losses. An important point is that while the AE program is effective in resulting in improvement in speech perception and production, it is not intended for every hearing impaired wearer – and judicious choice of subjects, of start frequencies, of the evaluative tools, and of proper counseling and rehabilitation is critical to its success.

Re-Evaluating the Efficacy of Frequency Transposition.

This article addresses the general value and efficacy of frequency transposition. Current methods of frequency lowering are discussed as well as results from studies looking at user preference, consonant identification in adults and children; potential improvement of speech in children. Candidacy selection and benefits of auditory training with frequency transposition are also discussed.

Efficacy of Linear Frequency Transposition on Consonant Identification in Quiet and in Noise.

This study was designed to examine the effect of linear frequency transposition on consonant identification in quiet (50 dB SPL and 68 dB SPL) and in noise at three intervals – the initial fit, after one month of use (along with auditory training) and a further one month of use (without directed training) of transposition. A single-blind, factorial repeated-measures design was used to study the effect of test conditions (3) and hearing aid setting/time interval (4) on consonant identification. Eight adults with a severe-to-profound high-frequency sensorineural hearing loss participated. Participants were fit with the Widex m4-m behind-the-ear hearing aids binaurally in the frequency transposition mode and their speech scores were measured initially. For all test conditions (50 dB SPL in quiet, 68 dB SPL in quiet, and 68 dB SPL in noise), a statistically significant difference (p < 0.05 level) was reached between the transposition condition measured at 2-months post-fitting and the initial fitting (with and without transposition) for fricatives only. The difference between transposition and the no-transposition conditions at the 50 dB SPL condition was also significant for the initial and one-month intervals. Analysis of individual phonemes showed a decrease in the number of confusions and an increase in the number of correct identification over time. Results suggest linear frequency transposition improved fricative identification over time.

Development of the ORCA Nonsense Syllable Test.

Many new processing features in hearing aids have their primary effects on information located in the high frequencies. Speech perception tests that are optimized for evaluating high-frequency processing are needed to adequately study its effects on speech identification. The goal of the current research was to develop a medium for evaluating the effects of high-frequency processing in hearing aids.

Critical factors in Ensuring Efficacy of Frequency Transposition I: Individualizing the Start Frequency.

This paper is the first in a two-part series that addresses how to fit the Audibility Extender (AE) feature in the Inteo ISP hearing aid successfully. In this paper, the authors discussed with analogies that the start frequency, or the frequency beyond which transposition takes place, is critical to the success of transposition. Too low a start frequency may under-amplify the wearers; and too high a start frequency may not yield sufficient transposition. Use of the recorded /s/ sound was suggested as an approach to individualize the start frequency. Several cases were also provided to demonstrate the importance of proper start frequency.

Critical Factors in Ensuring Efficacy of Frequency Transposition II: Facilitating Initial Adjustment.

This is the second part of the two-part series that attempts to shed light on how the transposition algorithm may be used successfully. As it turns out, success with the AE program may be maximized with individual “training” or sensitization to sounds. This paper described two programs for aural sensitization to sounds, including the description of an audio CD exercise that Widex developed to help facilitate AE wearers to tune in to specific sounds.

Criteria for Evaluating Linear Frequency Transposition in Children.

This paper discussed the importance of using appropriate evaluative criteria when assessing the efficacy of linear frequency transposition (audibility extender in Inteo). Specifically, it discussed the audiological criteria (such as the aided thresholds and identification of high frequency sounds and words) and speech criteria (such as articulation skills and voice loudness and pitch). The case reports of two children, who were part of a larger pediatric study of the audibility extender, were reported in the paper.

Use of Linear Frequency Transposition in Simulated Hearing Loss.

The study demonstrated the usability of new acoustic cues provided by the Inteo Audibility Extender (linear frequency transposition). The importance of auditory training in realizing the benefit was evaluated. Nine normal hearing participants were recruited. Their recognition of voiceless phonemes in CV, VC, and CVC context processed with and without linear frequency transposition was evaluated in the presence of a simulated high frequency hearing loss at and above 1600Hz. Identification test was carried out four times. Between each test session, participants completed 15 minutes of self-paced training using transposed stimuli. Prior to any training, transposition did not improve phoneme identification scores. Training of 30 minutes improved the overall identification scores of the transposed stimuli over the non-transposed stimuli by 14.4%. These results demonstrated that frequency transposition produces acoustic cues that normal hearing listeners with a simulated hearing loss at and above 1600Hz can be trained to utilize.

Effect of Linear Frequency Transposition on Speech Recognition and Production of School-Aged Children.

This study looked at the clinical efficacy of linear frequency transposition (LFT) for a group of school-aged children. Phoneme recognition and fricative articulation performance were compared for 3 conditions: 1) with the children’s own hearing aids 2) with an advanced hearing instrument utilizing LFT and 3) with the same instrument without LFT. Nonsense syllable materials were administered at 30 and 50 dB HL input levels. Fricative articulation was measured by analyzing speech samples of conversational speech and oral reading passages. Repeated Measures General Linear Model was utilized to determine the significance of any noted effects. Results indicated significant improvements in vowel and consonant recognition with LFT for the 30 dB HL input level. Significant improvement in the accuracy of production of HF fricatives after 6 weeks of use of LFT was also observed. These results suggest that LFT is a potentially useful hearing aid feature for school- aged children with a severe-to-profound HF sensorineural hearing loss.

Interpreting the Efficacy of Frequency-Lowering Algorithms.

Despite a long history of research and commercial efforts, hearing aids with frequency-lowering algorithms have become popular only recently. Widex re-introduced the concept of linear frequency transposition in its Inteo hearing aid in 2006 under the name Audibility Extender. Since then, we have explored various avenues to better understand how such a feature can be fitted and its use facilitated. Just as important, we also studied (and developed) research tools that may be optimal for evaluating such an algorithm. Our effort led us to report on the efficacy of such an algorithm in a simulated hearing loss, in an open-tube fitting, in children, and in adults in quiet and in noise. We have learned that demonstrating the efficacy of a frequency-lowering algorithm is not a straightforward matter. We would like to share our experience in this paper.

Frequency Transposition: Training is Only Half the Story.

It has been almost 5 years since Widex reintroduced frequency transposition as an approach to regain audibility of the high frequencies that are either unaidable or unreachable. Since the introduction of the Audibility Extender (AE), we have conducted several studies using adults and children as subjects to demonstrate its efficacy. In general, we have demonstrated that the use of AE with optimally selected settings, when paired with proper training and use of the device, yielded positive changes in the wearer’s identification of speech sounds, especially of voiceless and fricative sounds. Such benefits were seen in both quiet and noise conditions. This paper will shed additional evidence on the efficacy of the AE and the importance of training.

Earmold & Venting
Changing With the Times: Applying Digital Technology to Hearing Aid Shell Manufacturing.

This article described the steps involved in custom-shell making using the conventional approach and using the latest laser technology used by Widex – CAMISHA. The paper identified the weaknesses of the conventional approach and illustrated how the CAMISHA approach may improve upon the reliability, consistency of fit, and efficiency of shell making.

Real-World Performance of a Reverse Horn Vent.

This article reports on the evaluation of the reverse horn vent that Widex has been using in its custom products. The reverse horn vent is one that has a smaller vent opening on the lateral end of the hearing aid which gradually increases in diameter as it transverse medially. The study showed that such a vent system increases the effective vent diameter. For a 1/2/3 reverse horn vent (1 mm lateral diameter and 3 mm medial diameter), it reduces the occlusion effect by about 2-3 dB; however, it also decreases the maximum available gain by 2 dB. No other performance differences were noted. The results suggest that such a vent system may be used to increase the vent diameter when space is an issue.

Vent Configurations on Subjective and Objective Occlusion Effect.

This study examines the relationship between subjective and objective occlusion effects as a function of changing vent diameters and configurations. Its relationship to the compliance of the middle ear was also examined. The results showed that (1) there is a systematic relationship between effective vent diameter and subjective and objective occlusion effect; (2) the relationship was more systematic in the objective occlusion effect measurement; (3) there is a relationship between subjective and objective occlusion effect – a higher objective OE typically is associated with a larger subjective OE rating; (4) compliance of the middle ear system affects the objective OE measured. These results showed that each mm increase in vent diameter results in about 4-5 dB decrease in OE. A 3 mm vent diameter, on average, is able to reduce a significant amount of OE such that around 5-7 dB of objective OE results.

How do Vents Affect Hearing Aid Performance?

The authors reviewed how venting may affect the final output of a hearing aid. It postulated that the SPL at the eardrum of a wearer included amplified sounds, direct sounds from the vent, and bone-conducted sounds. It then reviewed how vent diameters affect the loss of low frequency output, limiting the maximum available gain before feedback, and soft speech recognition in quiet. In addition, it reviewed how vent diameters affected the bone-conducted signals (i.e., occlusion effect) as well as sounds that are transmitted directly through the vent diameter. A recommendation on optimal vent diameter was made as a result of these considerations.

Where an Accurate Fitting Begins: Assessment of In-Situ Acoustics (AISA).

This paper summarizes the rationale and actions of the vent compensation algorithm pioneered by Widex in the Inteo hearing aid. In short, the AISA procedure first estimates the equivalent vent diameter of a wearer/hearing aid using max gain information obtained during a feedback test. Armed with the equivalent vent diameter information, the algorithm corrects for the measured sensogram so the “real” hearing loss is determined. This allows gain to be prescribed more accurately. Afterwards, the prescribed gain is compensated by the magnitude of the vent effect so the output meets the desired gain target. The benefit of AISA is the assurance of target gain/output without the need for real-ear measurement.

Comparison of Vent Effects between a Solid Earmold and a Hollow Earmold.

Hollow earmolds have become a popular type of earmold used in thin-tube, micro-sized hearing aid fittings. It is desirable for clinicians to be familiar with their characteristics and limitations. This investigation compared the effects of vent diameter between a traditional solid earmold and a hollow earmold that is used in modern thin-tube hearing-aid fittings. A single-blind, 2 x 4 factorial design was used. Eight adults with a high-frequency hearing loss participated. Custom earmolds for use with thin-tube hearing aids were made for each participant. Two types of earmolds were made: a solid earmold with a traditional vent length and a hollow earmold where the thickness of the shell was the length of the vent. Vent diameters were 0 mm, 1 mm, 2 mm and 3 mm. The vent effect was evaluated on real-ear aided response, real-ear occluded response during vocalization, subjective occlusion rating, insertion loss, and maximum available gain before feedback. Real-ear measurements were made with the Fonix 6500 probe-microphone real-ear system. A systematic vent effect was seen with each earmold type as the nominal vent diameter changed. For the same vent diameter, the vent effect seen with the hollow earmold was greater than that of the solid earmold. Because of the difference in vent length (and thus acoustic mass) between a solid and a hollow earmold, the effect of vent diameter in a hollow earmold is more pronounced than that seen in a solid earmold of the same nominal vent diameter. Thus, a smaller vent diameter will be needed in a hollow earmold than in a solid earmold to achieve similar vent effects.

Ampclusion Management
Ampclusion Management 101: Understanding Variables.

This article reviews the factors that have been reported to contribute to the complaint of “ampclusion” or “strange own voice” problem. Such factors include those that have a shell origin – occlusion of the earcanal, depth of insertion, amount of leakage/vent, to those that have an amplifier origin – higher low frequency input, excessive low frequency gain, insufficient gain, saturation distortion, excessive group delay etc. In addition, the role of counseling (or setting right expectation) was also listed as a contributing factor.

Ampclusion Management 102: A 5-step Protocol to Remediation.

Based on the factors identified in the Ampclusion Management 101 article, the authors discussed a 5-step protocol in this article for the management of ampclusion. The five components of this protocol includes: setting the right expectation, selecting the optimal hearing aid characteristics (and accessories), verifying for an optimal fit (both acoustic and physical), determining the need to intervene, and diagnosing the origin of the ampclusion complaint with the right remediation. An Ampclusion Checklist is also included to facilitate clinical use of this approach.

Ampclusion 103: Managing High Frequency Hearing Loss.

This article went through the theoretical reasoning as well as the experimental demonstration that the “hollow voice” complaint reported by people with primarily a high frequency hearing loss is “shell” origin. This is because the real-ear aided response during vocalization of /i/ is seldom higher than the real-ear occluded response during vocalization below 1000 Hz for these individuals. This occurred because little gain is prescribed in the lows for such individuals and the magnitude of the occluded response is much higher than the magnitude of the amplified or aided response. Thus, the total real-ear output is primarily dominated by the occluded response. The clinical implication is that one must manage their “hollow voice” complaint through modification of the shell (such as changing vent dimensions and depth of shell insertion) and not adjustment of low frequency gain settings on the aids.

Managing Own Voice Problem that has an Amplifier Origin.

This is a case report illustrating the use of the Widex Amplcusion Checklist as well as illustrating that occlusion complaint is not always associated with too much low frequency output in the ear-canal. In this case, insufficient low frequency output (re: previous experience) may also result in the occlusion complaint.

BTE Coupling & Efficacy (Including RIC/Open & Thin Wire Tubing)
Efficacy of an Open Fitting Hearing Aid.

This article summarizes the advantages and limitations of opening fittings in hearing aids. In addition, it reported on the technical specification and efficacy data on the new Diva élan, an open-fitting hearing aid that is designed to eliminate occlusion while preserving as much audibility and signal-to-noise ratio as possible. In the study, ten subjects with primarily a high frequency hearing loss were fit with the Diva élan hearing aid and were evaluated on a battery of measures. Not surprisingly, the occlusion effect was eliminated with the use of the Diva élan. However, the required signal-to-noise ratio for 50% HINT performance was improved by almost 3 dB with the use of the élan over the unaided condition and the aided condition of the élan in an omnidirectional and no noise reduction mode. Although the SNR improvement of the élan was lower than that seen in the Diva hearing aid, this magnitude of improvement was sufficient to bring the speech in noise ability of the test subjects to be within 1 dB of those with normal hearing on the same test.

Speech in Noise Performance of a Micro-Size BTE.

This article describes the reasons why the directional microphone performance on a micro-size hearing aid may not be assumed because of the constraints on microphone placement. This lowers the directivity index of the hearing aid, and if not considered, could lower the SNR effectiveness of the hearing aid. In order to ensure that the m-model hearing aid is effective in noise, we tested 19 subjects with various degrees and configurations of hearing loss with the IN-9 and IN-m micro-size hearing aid with open-ear fittings and occluded fittings. There was no difference in SNR performance between the IN-9 and IN-m hearing aids. Furthermore, as much as 8 dB of SNR improvement was observed with the IN-m configured with the directional microphone and speech enhancer over the omnidirectional microphone mode. In an open-ear fitting, as much as 4 dB SNR improvement was observed. Post-microphone processing was attributed to the observations.

Hearing Aid Selection and BTEs: Choosing Among Various “Open-Ear” and “Receiver-In-Canal” Options.

This article described the six configurations in which today’s BTE hearing aids can be coupled to an earmold and offered a simple way to distinguish among them. They include “standard tube, open ear”, “standard tube, occluded-ear”, “thin-tube, open ear”, “thin-tube, occluded-ear”, “thin-wire, open ear” and “thin-wire, occluded-ear” fittings The chief issues behind the distinction between “open-ear” vs. “occluded ear”, “standard-tube” vs. “thin-tube” and “thin-tube” vs. “thin-wire (RIC)” are discussed. The myths about a receiver-in-canal (RIC) fitting are also discussed.

Fine Tuning Concepts
Using the I/O Curve to Help Solve Subjective Complaints with WDRC Hearing Instruments.

The author illustrated how one can use the I-O curve of a compression hearing aid to solve subjective complaints from wearers of such hearing devices. If one can estimate the input level at which the subjective complaint is based, one can adjust the specific hearing aid parameter to solve the complaint.

How Flow Charts Can Help You Troubleshoot Hearing Aid Problems.

The author provided a rationale for the use of flow-charts to aid in problem-solving hearing aid complaints. Two examples, “low gain before feedback occurs”, and “my voice sounds funny” were provided as illustrations on how this tool can be effectively used along with the solutions of these two complaints.

Fine Tuning Multi-Channel Compression Hearing Instruments.

The author discussed an effective communication strategy followed by illustrations of how one can use the Widex Solution Identification Worksheet to solve wearer’s complaint. Specifically, the following areas were discussed:

  • Input-output curves and multichannel compression hearing aids
  • Effective communication strategy to clarify the wearer’s reaction
  • Effect of adjusting gain for soft, moderate, and loud input signals
  • Effect of adjusting gain for low, mid, and high frequency channels

Short-Term Data Logging – Another Tool for Fine-Tuning Hearing Aids.

This paper reviewed the advantages of data logging and examined the differences between a long-term data logger and a short-term data logger. In short, while long term data logging provides usage information, the acoustic details of a single environment that may be troubling for the wearer is not available. Thus, in the Inteo, a short-term data logger is also available that allows the wearer to record one minute of the troubling acoustic environment that the clinician can download and review in order to gain insights during trouble-shooting. A recommendation on how to integrate this feature with the fine-tuning gain parameters was provided.

MPO: A Forgotten Parameter in Hearing Aid Fitting.

This paper discussed the importance of selecting a hearing aid with a sufficiently high Maximum Power Output (MPO) so that the output of the hearing aid would not be unnecessarily limited to a level below the wearer’s acceptable loudness level or suffer a poorer signal-to-noise ratio (SNR) or both. A theoretical rationale for that speculation, as well as waveforms showing the audio recordings of hearing aids with different levels of MPO were provided for demonstration.

Effect of Maximum Power Output and Noise Reduction on Speech Recognition in Noise.

The maximum power output (MPO) of a hearing aid was typically discussed in the context of avoiding loudness discomfort. However, an MPO that is too low, as in the cases to avoid discomfort for people with a severe loudness tolerance problem and hearing losses that exceed the fitting range of the hearing aids, could negatively affect sound quality and speech intelligibility in noise. The current study was designed to demonstrate the degradation in speech intelligibility in noise on the HINT (Hearing in Noise Test) when the MPO of the wearers’ hearing aids was lowered by 10 dB from the default. The interactions with noise reduction (NR) algorithms (classic [NR-classic] and Speech Enhancer [NR-SE]) were also examined.

Acclimatization
Adaptation to Enhanced Dynamic Range Compression (EDRC) – Examples from the Senso P38 Digital Hearing Aid.

This article uses the findings of a study on the P38 power hearing aid as an illustration of the dilemma that clinicians may face in deciding the course of action when the results of the initial fit are objectionable to the wearers. The results of the P38 study on 20 adults showed that its low compression threshold and high level compression were effective in improving the wearer’s speech understanding ability over time. However, the same features also resulted in initial negative subjective reactions from the wearers. This article reminds clinicians that in attempting to resolve a wearer’s complaints, it is necessary to understand fully the operation of the recommended hearing aid, the wearers hearing loss and hearing aid history, the specifics of the wearer’s complaints, and the results of the fitting.

Evidence of Acclimatization in Persons with Severe-to-Profound Hearing Loss.

In this article, the authors reported on a study with the P38 super-power hearing aid on speech recognition scores over time in people with a severe-to-profound degree of hearing loss. It was speculated that because of the severity of the hearing loss, this patient population will be least likely to hear the softer parts of everyday sounds and will be most likely to show acclimatization if they were provided with audibility of the softer sounds brought forth by the P38’s low compression threshold. Twenty severe-to-profound hearing impaired subjects wore the P38 hearing aids and were tested at initial, one-month, and three-months after the initial visit. In addition to seeing improved speech score when compared to their own hearing aids on the SPIN test at a 50 dB SPL level during the initial visit, subjects also showed an improvement at the one-month evaluation but not the three month evaluation. The pattern of improvement was also different between the high probability words and the low probability words across stimulus conditions. The clinical implications of the results are discussed.

Verification Strategies for Non-Linear Hearing Aids
Differences in Sensation Level between the Widex Sound Tracker and Two Real Ear Analyzers

The authors report mean differences in the estimated sensation level of Sound Tracker compared to the measured sensation level of the Verifit and 6500 were

Variables Affecting the Use of Prescriptive Formulae to Fit Modern Non- Linear Hearing Aids.

The authors listed some of the reasons why it may not be appropriate to follow strictly any prescriptive targets in verifying the output of today’s digital nonlinear hearing aids. Among those reasons are the effects of: number of channels, detector type, compression threshold, processing below the compression threshold, and the release time. A “technical” explanation was provided for each reason. All these variables could affect the outcome of a hearing aid even though a target is matched. The authors also suggested that in the future manufacturers will become responsible for developing their own guidelines to verify the output of their hearing aids.

Verifying the Output of Digital Nonlinear Hearing Instruments.

The authors listed the difficulties (and solutions) associated with verifying the real-ear output of today’s nonlinear hearing aids, especially with digital hearing aids with advanced signal processing algorithms.

Verification of Nonlinear Hearing Aids: Considerations for Sound-Field Thresholds and Real-Ear Measurements.

Audiologists and dispensers have used the aided thresholds as a tool to verify linear hearing aids for many years. Its use with nonlinear hearing aids may require a different interpretation. In this article, the authors reviewed the meaning of the aided thresholds as an index to show the softest sound that a wearer can hear with the nonlinear hearing aids. In addition, the authors also discussed where the optimal aided thresholds should be for linear and nonlinear hearing aids, as well as the exceptions to this optimal value. The measurement variables that could affect the accuracy of the aided thresholds are also discussed. Finally, the authors reviewed the relationship between functional gain measures and insertion gain measures, indicating that these measures yield complementary information and that both should be determined during routine hearing aid fitting.

Changing with the Times: Re-Examining the Aided Threshold.

The value (and the right interpretation for) of the aided threshold for nonlinear hearing aids was discussed in this article. The authors indicated that for a nonlinear hearing aid without VC adjustment, the aided threshold represents the softest sound that the individual can hear with the hearing aid. This index is neither predictable from insertion gain measurement (because of nonlinearity) nor provides the same information as insertion gain measurement. As such, the authors argued that the aided threshold should be used in conjunction with insertion gain measures (if desired) for good clinical verification.

Using In-Situ Thresholds to Predict Aided Sound-Field Thresholds.

In this article, the authors discussed how the use of in-situ threshold measurement (i.e., sensogram) may permit one to predict the aided sound-field thresholds. The only factor that may alter the prediction is the individual free-field to microphone transfer (FF2Mic). The authors also reported a preliminary study compared the predicted and measured aided sound field threshold. Agreement to within 5 dB was found for the average subjects for all frequencies tested (500 to 4000 Hz). However, some subjects (2) may have individual deviations as much as 15 dB at some frequencies. Considering the time saved, the use of predicted threshold was proposed as a first line of verification.

Changing with the Times: Choice of Stimuli for Hearing Aid Verification.

This is a tutorial on the use of different acoustic stimuli (pure-tones, complex signals, and composite signals) for verifying hearing aid performance. In particular, the differences between using a pure-tone sweep, the ANSI 92 speech noise, and the ICRA speech noise on the performance of linear and nonlinear hearing aids are highlighted. While the gain on a linear hearing aid may not be sensitive to stimulus difference, the gain and output of a nonlinear hearing aid is dependent on the stimulus that is used to measure its performance. Furthermore, the outcome is dependent on the number of channels and the type of special processing (e.g., noise reduction) within the nonlinear hearing aids. The practical implications of these differences and a recommendation on how to verify nonlinear hearing aids were discussed.

Reconsidering the Concept of Aided Threshold for Nonlinear Hearing Aids.

This is a tutorial explaining why the aided threshold should be included as a metric in verifying the performance of nonlinear hearing aids. Included in this manuscript are discussions on:

  • The aided threshold represents the softest sound a wearer of nonlinear hearing aid hears (and why is it different from linear hearing aids)
  • Factors affecting the magnitude of the aided threshold
  • Electroacoustic variables
  • Measurement variables
  • Differences between functional gain and insertion gain
  • How in-situ threshold measurement allows prediction of aided threshold
  • A summary of a pilot study comparing the measured and predicted aided threshold from the Compass I-O curve
  • A mathematical treatment on the conversion from dB SPL to the dB HL reference used in all the Compass screens
Using Digital Hearing Aids to Visualize Real-Life Effects of Signal Processing.

This paper describes the SoundTracker feature that is available on Compass for the Diva and the Vita hearing aids. In essence, the SoundTracker utilizes the microphone on the hearing aid and turns it into a multichannel sound-level meter. It displays the input to the hearing aid microphone in its various channels, as well as the estimated output at the TM of the wearer based on the known Input-Output characteristics of the hearing aids. This paper described how this feature can be utilized (e.g., counseling, fine-tuning, trouble-shooting etc), as well as some of the precautions when using this feature.

Hearing Aid Fittings and the Use of Simulated Sound Environments.

This paper described the rationale and implementation of the LifeSound, a collection of calibrated sound effects that can be used during the counseling, fitting, and fine-tuning of hearing aids during the hearing aid process. The difference between the LifeSounds and other sound effects is that it used the Diva hearing aid as the Sound Level Meter for its calibration (instead of using expensive external SLM). This ensures that the system can be practically implemented in most clinical facilities. Examples of how a simulated listening environment may be useful in the clinical setting were discussed.

Reliability of the Aided Sound-Field Thresholds in Nonlinear Hearing Aids.

This paper described the results of a study where the aided and unaided sound-field thresholds of 12 hearing impaired individuals wearing the Diva hearing aids (4 with BTE, 4 ITE, and 4 CIC) were measured. It was previously reported that the standard deviation of the sound-field aided threshold of linear hearing aids was unacceptably high (Hawkins et al., 1986 – about 6 to 8 dB). Subjects in this study were properly instructed not to show any excessive movement, and stimuli were presented in an ascending, 5-dB step procedure to avoid artifacts from compression. Using the present procedure, the standard deviation was about 2-3 dB, significantly smaller than the previously reported value. Furthermore, the magnitude of the SD was similar to that of the unaided SF thresholds. This suggests that the aided sound-field thresholds can be reliable if sufficient care was used in its determination.

Pediatric
Hearing Aid Design Considerations for Optimally Fitting the Youngest Patients.

The author reviewed the developmental needs of children (from birth to teenage) and specified how a hearing aid should process sounds in order to optimally fit this group of wearers. The important processing features include:

  • In-situ threshold measurement to ensure accuracy of fit
  • Flexible electroacoustic adjustment to accommodate changes (growth, hearing loss)
  • Slow-acting wide dynamic range compression to
  • Ensure audibility and comfort
  • Preserve temporal integrity of input (speech)
  • Ensure adequate gain for changing input levels
  • Low compression threshold at 20 dB HL to ensure audibility
  • Directional microphone and DAI compatibility to enhance signal-to-noise ratio
Use of a Digital Hearing Aid with Directional Microphones in School-Aged Children.

The authors reported on a clinical study with 20 hearing-impaired children between 8 and 12 years of age in the Portland School District. Nine of the children had a mild-to-moderate degree of hearing loss and eleven had a moderate-to-severe degree of hearing loss. Subjects were fit with the C9 (for the mild loss) and the C19 (for the moderate/ severe loss) directional SENSO hearing aids. Subjects wore the aids for over 30 days and were tested on the W-22 word list at 65 dB SPL in three SNR of +7, 0, and –7 dB (speech front and noise back condition), the LIFE questionnaire, as well as a parent questionnaire.

The Effect of Non-Linear Amplification and Low Compression Threshold on Receptive and Expressive Speech Ability in Children w/Severe to Profound Hearing Loss.

This study was conducted in Spain evaluating the effectiveness of the super-power P38 hearing aids on a group of hearing impaired school children who had a severe-to-profound degree of hearing loss. Twenty school children were fitted binaurally and their performance with the P38 was evaluated in the sound-field with aided threshold measurement, speech recognition testing at soft and conversational levels, as well as subjective questionnaires.

Fitting Digital Nonlinear Power Aids on Children with Severe-to-Profound Losses.

This study was conducted with the P38 hearing aid in the USA using the same protocol as the Spain study. Eight children from the University of Colorado Health Sciences Center (UC) and five from the University of Kansas Medical Center (KUMC) participated. Subjects wore the P38 hearing aids for a period of 3 months, and were evaluated at the initial visit (or fitting), one month and three months post-fitting. Evaluative tools included aided sound-field thresholds, speech recognition in quiet (35 dB HL) and in noise (+10 SNR), LIFE questionnaire, Widex questionnaires, and speech production measures.

Performance of Children Fitted with Multi-Channel, Nonlinear Hearing Aids.

This is the first progress report from Widex’s Pediatric Hearing Assistance Program (PHAP) that was initiated in 2001. This report described the impetus of the PHAP, the data collection protocol, and the initial results from two groups of children – one from 6 to 17 years old (N=18) and the other from birth to 3 years (N=12). These children have varying degrees and configurations of hearing losses. For the older children, their performance on standardized speech test at a soft level (35 dB HL), a conversational level (50 dB HL), and in noise (+10 SNR) were reported. In addition, the CHILD and Widex’s questionnaires were administered. A key observation with this group is the similarity in speech recognition scores obtained between a soft level and a conversational level – supporting the premise that a nonlinear hearing aid ensures audibility and comfort. A key observation in the younger group of children is the number of parents who reported noticing an improvement in their children’s speech production ability (in addition to an improvement in listening behaviors). This is an important documentation of the potential impact of digital nonlinear hearing aids on the speech perception and speech production abilities of hearing-impaired children.

Language Progress of Children Using Advanced Hearing Aids: A Multi- site Clinical Research Project Report.

This paper reports on some of the preliminary speech and language results of children fit with Widex digital hearing aids (mostly Diva) as part of the Pediatric Hearing Assistance Program (PHAP). The data were collected from over 10 sites over the last 5 years since the inception of the PHAP. As expected, the speech and language skills of these children progressed with the use of Widex hearing aids at a rate faster than they would have without the Widex aids. But more interestingly, it was noted that those who were aided at a younger age (than 5 years) showed a faster rate of progress than those aided at an older age.

Experience with Using Auditory Brainstem Response (ABR) Thresholds to Fit Infants with a Digital Hearing Aid.

The authors reported on their experience using frequency specific ABR thresholds to initially set the Senso hearing aids for infants. Three cases were reported with the youngest infant at 5 weeks. The outcome/progress with these fittings was reported, as well as some practical recommendations were offered.

Factors Ensuring Consistent Audibility in Pediatric Hearing Aid Fitting.

In this article, the authors reviewed the factors that could affect the consistency at which a child receive adequate audible information from the selected hearing aids. These factors include:

  • Accurate assessment of hearing sensitivity
  • Ensuring best form of amplification – binaural and wide dynamic range compression
  • Ensuring optimal gain at all input levels
  • Preserving as much input cues as possible with slow-acting compression
  • Ensuring specificity of processing with multiple channel hearing aids
  • Ensuring favorable signal-to-noise ratio with minimal sensitivity loss
  • Ensuring the ability to use the prescribed gain successfully with feedback management
  • Ensuring minimal artifacts under all conditions
  • Ensuring that human factors are considered
Personal Amplification for School-Age Children with Auditory Processing Disorders.

This paper provides a rationale for why open-fit, mild-gain WDRC hearing aids with a directional microphone may be an alternative tool or approach to provide a better signal-to-noise ratio (SNR) for normal hearing children with auditory processing difficulties. In addition, it reported on the findings of a study on 14 school age children with diagnosed APD and fitted with binaural Vita élan open-fit hearing aids. Their speech in noise performance – including identification of NU-6 words, and attention on the ACPT test, as well as questionnaires such as the CHAPS were reported. For some children, the use of hearing aids with a directional microphone can provide some improvement in social, academic, and behavioral performance of these children.

Efficacy of an Adaptive Directional Microphone and a Noise Reduction System for School-Aged Children.

A non-randomized, experimental study utilizing double-blinding was implemented to investigate differences in word recognition performance of school-aged children utilizing adaptive directional microphone and noise reduction (NR) features. Children from two educational facilities participated in this study. Signal-to-noise-ratio (SNR) benefit of the adaptive directional system was estimated to be 7.6 dB. No SNR benefit was measured for the NR feature; however no decrease in performance was observed either. Subjective difficulty for desired sounds originating from various azimuths was not significantly greater in either the adaptive directional or NR modes. Results indicate that for the purposes of improving SNR, adaptive directional microphone systems, but not NR systems, are potentially efficacious hearing aid (HA) fitting options for school-aged children.

Speech & Language of Children Using Hearing Aids with Adaptive Directional & Noise Reduction Features.

This paper reviews longitudinal speech-language outcomes of a group of school age children using hearing aid noise reduction and adaptive directional features. These results, obtained through collaboration between school audiologist and speech-language pathologist, reveal that receptive and expressive language scores are stable or improved over a three-year period of use.

Hearing Aids for Children with Auditory Processing Disorders?

This article provides a review of the rationale for using hearing aids with children diagnosed with auditory processing disorders (APD). In addition, it summarizes the results of a study that considered how hearing aids may be configured to meet the needs of children with APD.

FM & Direct Audio Input (DAI)
Achieving Hearing Aid and FM System Transparency.

This article provides a step-by-step guide for measuring the transparency of an FM system coupled to a high-technology hearing aid. The specific procedures are necessary to ensure stable results for each measurement. A case study discusses the coupling of the Widex Senso Diva to the MicroLink by Widex FM System.

Coupling FM Systems to High-Technology Digital Hearing Aids.

FM systems are still the preferred choice for increasing the SNR in a noisy listening environment. Smaller FM systems, such as the MicroLink by Widex can easily be coupled to Widex high-technology digital hearing aids. When electroacoustic measurements are made on FM+HA systems, specific procedures need to be followed to ensure that the results are reliable and repeatable. In this article, the specific procedures are provided along with figures demonstrating the necessity for these procedures.

A Three Step Procedure to Assess FM Transparency and FM/HA Ratio with Digital Hearing Aids.

This article illustrated the steps that one should follow to verify FM transparency and FM/HA ratio when it is connected to a hearing aid. The three steps included: (1) evaluating the hearing aid frequency response alone with a conversational level input; (2) evaluating the hearing aid output when connected to an FM system with a conversational input (e.g., 65 dB SPL) presented to the FM microphone; and (3) evaluating the hearing aid output when connected to an FM system with a loud input (e.g., 80 dB SPL) presented to the FM microphone. The Frye 6500 and the Audioscan Verifit systems were used to illustrate the steps.

Novel Use of Hearing Instruments
A Hearing Aid Solution for Music

The impact of Widex True Sound high input dynamic range technology was examined in a study of 10 hard of hearing musicians. Data supported clear preferences for the Dream technology for the sound clarity and naturalness.

Using DSP to Screen Hearing Aid Component Problems.

The rationale and mechanism of a Self-Test to screen potential hearing aid component defect in the Diva hearing aid was reported. In addition, the results of a validation study on the Self-Test were reported. Using in-house technicians as the benchmark, 200 custom Diva hearing aids that were sent in for repair were tested with the Self-Test and then by in-house technicians for typical evaluation. The results showed that the Self-Test has a high hit rate in that 87.5% of the custom products were correctly identified by the Self-Test. Indeed, when the Self-Test consistently indicated a problem, a problem is always identified by the technicians. The proper ways to use the self-test and interpret the results were discussed.

Using Digital Hearing Aids to Visualize Real-Life Effects of Signal Processing.

This paper describes the SoundTracker feature that is available on Compass for the Diva and the Vita hearing aids. In essence, the SoundTracker utilizes the microphone on the hearing aid and turns it into a multichannel sound-level meter. It displays the input to the hearing aid microphone in its various channels, as well as the estimated output at the TM of the wearer based on the known Input-Output characteristics of the hearing aids. This paper described how this feature can be utilized (e.g., counseling, fine-tuning, trouble-shooting etc), as well as some of the precautions when using this feature.

Hearing Aid Fittings and the Use of Simulated Sound Environments.

This paper described the rationale and implementation of the LifeSound, a collection of calibrated sound effects that can be used during the counseling, fitting, and fine-tuning of hearing aids during the hearing aid process. The difference between the LifeSounds and other sound effects is that it used the Diva hearing aid as the Sound Level Meter for its calibration (instead of using expensive external SLM). This ensures that the system can be practically implemented in most clinical facilities. Examples of how a simulated listening environment may be useful in the clinical setting were discussed.

Personal Amplification for School-Age Children with Auditory Processing Disorders.

This paper provides a rationale for why open-fit, mild-gain WDRC hearing aids with a directional microphone may be an alternative tool or approach to provide a better signal-to-noise ratio (SNR) for normal hearing children with auditory processing difficulties. In addition, it reported on the findings of a study on 14 school age children with diagnosed APD and fitted with binaural Vita élan open-fit hearing aids. Their speech in noise performance – including identification of NU-6 words, and attention on the ACPT test, as well as questionnaires such as the CHAPS were reported. For some children, the use of hearing aids with a directional microphone can provide some improvement in social, academic, and behavioral performance of these children.

Short-Term Data Logging – Another Tool for Fine-Tuning Hearing Aids.

This paper reviewed the advantages of data logging and examined the differences between a long-term data logger and a short-term data logger. In short, while long term data logging provides usage information, the acoustic details of a single environment that may be troubling for the wearer is not available. Thus, in the Inteo, a short-term data logger is also available that allows the wearer to record one minute of the troubling acoustic environment that the clinician can download and review in order to gain insights during trouble-shooting. A recommendation on how to integrate this feature with the fine-tuning gain parameters was provided.

The Hearing Aid as a Music Synthesizer.

This paper discussed the neurophysiology of music perception and reported on the “musical factors” that promote relaxation. The case for the use of fractals as a practical means to generate music in today’s digital hearing aid was made, along with a description of the synthesized music program, the Zen. A brief description of the mind440 hearing aid which the Zen is a major feature was provided as well. Finally, a description of a laboratory study that evaluates the efficacy of the Zen in relaxation was reported.

Hearing Aids for Children with Auditory Processing Disorders?

This article provides a review of the rationale for using hearing aids with children diagnosed with auditory processing disorders (APD). In addition, it summarizes the results of a study that considered how hearing aids may be configured to meet the needs of children with APD.

Miscellaneous
Battery Consumption in Wireless Hearing Aid Products – Datasheet vs. Real-World Performance

The authors review how more often than not, real-life battery performance can deviate from manufacturer datasheet measurements when hearing aid adaptive features, such as feedback canceling, noise reduction, and other features are activated. Clinicians should look for hearing aid data sheets to state current drain and expected hours of use, as well as the battery capacity. This information is needed to enable the hearing care professional to calculate what the battery consumption is likely to be.

Effects of Training on the Use of a Manual Microphone Shut Off in a BiCROS Device

Study findings support the value of an on/off switch on a CROS transmitter because it allows convenient selective transmission of sounds. This article also highlights the importance of instructions and practice in using the BiCROS hearing aid successfully.

Localization 103: Training BiCROS/CROS Wearers for Left –Right Localization

This study demonstrates that a BiCROS system with an easy On/ Off switch can provide loudness cues to aid in localization and therefore be considered a critical part of a CROS/ BiCROS system.

Improving Speech Intelligibility With Widex CROS

This Widex CROS clinical research study objective was to determine the improvement of speech intelligibility in noise with the WIDEX CROS and to determine specific everyday situations where the WIDEX CROS proved to be most beneficial to the user. The results from the objective testing showed that the WIDEX CROS technology significantly improves speech intelligibility of a person with single sided deafness when hearing in noise.

Factors Affecting Interference from Digital Cellular Telephones.

The authors explained why “buzzing” occurred when a digital cell phone was placed next to a hearing aid. In addition, approaches to minimize such “buzzing”, and why DSP hearing aids could further minimize such “buzzing” were discussed.discussed.

Changing with the Times: Managing Low-Frequency Hearing Loss.

This is a review article on the etiology and historic management of a low-frequency hearing loss and how current digital nonlinear hearing aids may improve the success in managing this loss configuration. Key features that digital technology has realized included multi-segmental nonlinear processing, multiple channel processing, noise reduction algorithm, and the availability of “memories” for paired comparison task. The fitting of two patients with a low-frequency hearing loss using the paired comparison procedure was also reported to demonstrate the diversity in frequency-gain preference.

Get SET to Maximize Success in Fitting and Office Management.

This article reviews the three software tools that Widex provides to its customers to maximize their business and patient success. They include the InfoTrack, an office management system that allows audiogram search and mail merge functions; the SoundTracker that allows visualization of input to and output from the Diva and Vita hearing aids; and the LifeSounds that allows the use of simulated real-world evaluation of hearing aid sound quality.

Development of the ORCA Nonsense Syllable Test.

Many new processing features in hearing aids have their primary effects on information located in the high frequencies. Speech perception tests that are optimized for evaluating high-frequency processing are needed to adequately study its effects on speech identification. The goal of the current research was to develop a medium for evaluating the effects of high-frequency processing in hearing aids.

Widex Builds for Future with a New "Green" Home and a "Clear" Route in Products and Research.

This article highlights the new “Green” Widex HQ in Denmark as well as the future vision of the Company. The 10th anniversary of ORCA-USA, a Widex research facility outside of Chicago, Illinois is also chronicled.

Enough is Enough: A Primer on Power Analysis in Study Designs.

The dispensing profession has always been driven by a reliance on evidence to support its activities. While various leaders in our field have outlined the different levels of evidence and specified the criteria to judge the validity of evidence, we continue to come across “evidence” that is quasi-evidence at best. Either the results of the studies are not treated statistically, or the statistical treatment lacks sufficient power to be meaningful. Such evidence can mislead readers to believe in the effectiveness of a particular feature when such efficacy is not present; or to believe in the ineffectiveness of a feature when its true efficacy has not been adequately evaluated. This paper briefly reviews an important factor that affects the interpretation of the results of a study — sample size — in hopes that the information presented will help clinicians and students better understand how to interpret the results of any clinical study.

Tinnitus (Zen)
The Hearing Aid as a Music Synthesizer.

This paper discussed the neurophysiology of music perception and reported on the “musical factors” that promote relaxation. The case for the use of fractals as a practical means to generate music in today’s digital hearing aid was made, along with a description of the synthesized music program, the Zen. A brief description of the mind440 hearing aid which the Zen is a major feature was provided as well. Finally, a description of a laboratory study that evaluates the efficacy of the Zen in relaxation was reported.

Effects of Acoustical Stimuli Delivered through Hearing Aids on Tinnitus.

The use of acoustic signals to mask, mix with, or ease the distress associated with tinnitus has been clinically employed for decades. It has been proposed that expanding acoustic options for tinnitus sufferers due to personal preferences is desirable. Fractal tones incorporate many useful characteristics of music while avoiding certain features that could be distracting to some individuals.

The Efficacy of Fractal Music Employed in Hearing Aids for Tinnitus Management.

The Zen program provides a relaxing sound background so adult hearing aid wearers may use it for relaxation in quiet where listening to the environment and/or speech is not critical. In the hands of those who are trained in tinnitus management, this may be a convenient and discreet sound therapy tool for hearing-impaired people with tinnitus. The following survey was conducted to determine if indeed clinicians who were trained in tinnitus management would find the Zen program useful for their tinnitus patients.

Effect of Counseling, Amplification and Fractal Tones in Tinnitus Management

A study that investigates the effectiveness of counseling, amplification and fractal tones in managing tinnitus

A Controlled Study on the Effectiveness of Fractal Tones on Subjects with Minimal Need for Amplification

An article that features the use of Zen alone, and of the integrated WZT approach in tinnitus patient management.

A clinical study that confirms substantial positive results with the use of Widex Zen Therapy in tinnitus patient management

An article that features the use of Zen alone, and of the integrated WZT approach in tinnitus patient management.

Do Tinnitus Patients Continue to Use Amplification and Sound Therapy Post Habilitation?

A look at the long-term effectiveness of an integrated tinnitus management approach (WZT) and the pattern of amplification and sound therapy use

Wireless Technology
Factors Affecting Interference from Digital Cellular Telephones.

The authors explained why “buzzing” occurred when a digital cell phone was placed next to a hearing aid. In addition, approaches to minimize such “buzzing”, and why DSP hearing aids could further minimize such “buzzing” were discussed.discussed.

Digital Wireless Hearing Aids, Part 2: Considerations in Developing a New Wireless Platform.

In a previous paper, we provided a tutorial on the principles of digital audio codec and outlined some of the components in a wireless hearing aid. In this paper, we will discuss the important factors to consider in a digital wireless hearing aid and how those considerations are integrated into the design of the digital wireless platform used by WidexLink, a new technology that enables the C-Integrated Signal Processing (C-ISP) used in the CLEAR440 hearing aids.

Digital Wireless Hearing Aids, Part 1: A Primer

Taking an audio signal and transmitting/receiving it digitally is a multi-stage process, with each step influencing the quality of the transmitted sounds. This article provides a primer about the steps involved in the process for both near- and far-field transmission of signals.

Shadow Corner Left Contact Us  |   All Rights Reserved © Copyright 2015 Widex USA, Inc. Shadow Corner Right