For years, it’s been the case that no matter how good the sound in a hearing aid is, it always sounds like a hearing aid. But now, a new technology virtually eliminates the source of this artificial sound and helps wearers enjoy a more natural sound experience.
Since the introduction of digital hearing aids in the 1990s, hearing aid users have had to accept that to get all the great features of digital hearing aids, they’d have to compromise on the sound quality – mainly because of what’s known as the comb-filter effect. 

The comb-filter effect arises because digital signal processing in the hearing aid delays the amplified sound compared to the direct sound that enters the ear through venting in the ear tip and through any leakage around it. 
Even with a delay of just a few milliseconds, the delayed processed sound and the direct sound move in and out of phase. This leads to peaks and troughs in the gain-frequency curve, and these peaks and troughs resemble the teeth of a comb – hence the name.

To users, the comb-filter effect is perceived as a distorted, hollow, artificial sound – as if you’re listening through a tube or a seashell. 

Enter Widex PureSound™

This sound experience has until now been an unavoidable trait of digital hearing aids with open and vented fittings. But thanks to a new paradigm in digital sound processing, it doesn't have to be  a problem any longer.  

PureSound is a program that comes with the new WIDEX MOMENT™ hearing aid. The program practically eliminates the comb-filter effect, along with its negative effect on sound quality, by lowering the average delay of the processed sound to less than 0.5 milliseconds. 

That’s a giant step forward, because even premium hearing aids typically have delays of between 3 to 8 milliseconds. These may seem like very short delays, but even a 3-millisecond delay results in comb-filtering and an artificial sound experience for the hearing aid wearer. 
Since the new PureSound program achieves a delay of just 0.5 milliseconds, it creates a much purer and more natural listening experience for the user. 
How does PureSound work?
The PureSound experience is enabled by Widex ZeroDelay™ Technology. This includes the ZeroDelay Pathway, which is an alternative to the Widex Classic signal pathway that powers the Universal and specialized programs.

The Classic pathway contains all the digital signal processing features you would expect from Widex, while the ZeroDelay Pathway uses adapted versions to deliver sound faster, with next-to-no comb-filter effect. 

Because the PureSound program still includes most of the features that you would expect from digital hearing aids, it’s very suitable as an everyday program for users with mild-to-moderate hearing losses. 

Hearing aids that benefit all users
The comb-filter effect problem is mainly an issue for completely open ear tips, but since instant ear tips are rarely entirely closed, it poses a potential problem for all instant ear tips. 

Instant ear tips account for over 80% of hearing aid sales in the US. This means that the comb-filter effect is potentially an issue for 4 out of 5 hearing aid wearer. Especially for those with mild-to-moderate hearing loss, who are more likely to have the open and vented fittings where the problem is most widespread. 

For users with more severe hearing loss, the WIDEX MOMENT™ Universal program still delivers the Widex focus on great sound quality. 

With these two processing options, WIDEX MOMENT™ hearing aids provide an optimal solution for all, including users who are new to hearing aids and will no longer have to struggle with getting used to the sound of delay.

What do users think about PureSound™? 
Read the research that examines the real-life benefits of PureSound in a guided sound walk study.