Stop the Whistle

By Lina Marie Barreneche

For decades feedback, whistling or squealing, has been a major complaint among hearing aid patients. The introduction of digital technology has significantly improved the acoustic stability of modern hearing instruments.

Modern feedback management systems enable hearing care professionals to offer much greater wearing comfort to their patients, thanks to WhistleBlock technology.

A further challenge of the state-of-the-art feedback management systems is that they can cause distortion of natural signals, such as music, telephone ringing or door bells. However new research is applied and improvements are made in every new product that is launched by the hearing aid industry.

Open fit hearing aids have been introduced and they seem to provide not only cosmetic benefit, but also the acoustic quality desired by every patient. Feedback is almost eliminated from these instruments.

There are several consequences of feedback on sound quality. An important issue to consider is the impact of acoustic feedback on the sound quality of the target signal. Commonly the implicit assumption is that feedback equals “whistling” to a pure tone. The frequency characteristic of the hearing instrument begins to change and a marked impact on sound quality occurs. The instruments may sound rough, modulated or harsh, i.e. artifacts and distortions start to occur.

Different approaches to feedback management have been introduced by hearing aids companies. The most successful approach is the adaptive feedback canceling system, which is very well known as top of the line hearing digital technology.