TRUSOUND TECHNOLOGY

TruSound technology helps to perfectly replicate and reproduce all the world’s sounds – allowing users to adapt to everything from speech to nature to conversation and music.

TruSound Stabiliser
Evidence suggests that hearing aid users prefer sound quality generated by a slow-acting compression system. But sometimes, slow-acting compressors aren’t enough. That’s why we developed TruSound Stabilisers.

TruSound stabilisers help preserve the high sound quality expected from the TruSound compression system – even in demanding situations. Stabilisers are designed to handle quick changes in sound environments, preventing smearing of the signals’ temporal and spectral contrast. 

Sudden changes in loudness
Loud noises do not have the same amount of gain as applied to quiet environments. When sound levels increase rapidly, hearing aids must react quickly to these changes – like when a user leaves a crowded room to answer a phone call. TruSound Stabilisers help even out the sound peaks so that sound is never too loud for the user. 

TruSound Softener
A study by Keidser et al. (2009) showed that transient sounds are often perceived as more annoying to hearing aid users than non-users. With TruSound softener, we minimize the irritation caused by these sounds without completely removing them.

Transient sounds come in all sound levels:

• Soft transient sounds include computer keystrokes and ticking clocks
• Medium transient sounds include clanging dishes and clattering cutlery
• Loud transient sounds include fireworks and hammer blows.

Loud transient sounds are less than one second long and rise to their peak loudness quickly. They often exceed the hearing aid user’s comfort level if the gain is not reduced. Soft and medium levels, however, need that gain to be able to be heard. With TruSound softener, all transient noise sounds can be identified and handled efficiently without affecting speech sounds. 

Soft sounds should be audible, speech should be intelligible, and loud sounds should be comfortable for hearing aid users. The TruSound softener helps accomplish this by reducing gain relative to the user’s hearing loss to provide a comfortable and realistic rendition of any sound environment. 

TruSound Compression
Hearing aid compressors adjust gain according to the current sound environment and the user’s hearing loss. Target gains are based on three sound levels: soft sounds, normal speech levels, and loud sounds. 

• For soft sounds, Widex aims to match the loudness perception of a normal-hearing person closely. 
• For typical speech levels, the goal is optimal speech intelligibility. This involves an equalization scheme, where each frequency region is amplified to make speech cues audible. Gain is also optimized according to the user’s sound environment.
• For loud sounds, the strategy is to ensure that the user perceives them as loud but not uncomfortable. 

The speed at which gain is regulated in the compressors is an important factor for sound quality. Research shows that a slow-acting compression system results in the best sound quality. Users generally prefer low compression rates for most input levels. 

TruSound Compression accomplishes this by adjusting gain according to the general sound level and the sound quality of a linear system. This helps preserve the spectral and temporal contrasts in speech signals.

TruSound Automatic Output Control
Automatic Output Control (AOC) The final stage of hearing aid processing involves ensuring that high-quality sound is played back to the user. Automatic Output Control (AOC) accomplishes this by monitoring the sound signal sent to the receiver to avoid signals that are too loud for it to handle. This involves two steps: 

• The narrowband AOC – First, the AOC checks if each channel’s power level exceeds the Maximum Power Output set in the fitting software for the user. If it does, the AOC will reduce the gain in the relevant channel. If the signal isn’t loud enough to affect the adjacent channels’ levels, the gain will be adjusted there too. 
• The broadband AOC – The AOC measures the exact power in the final signal to avoid output signals that are too loud for the user. By utilizing an existing small delay in the signal chain, the measurement can be carried out early enough for the system to handle the signal before playback.