Feedback Cancellation

Feedback in hearing aids occurs when amplified sound from the hearing aid receiver leaks back into the microphone and is re-amplified, producing a high-pitched whistle or squeal. This typically happens when the hearing aid does not seal properly in the ear, when a hand or telephone comes close to the device, or when the fitting is not correct for the ear.

Feedback cancellation is a feature in modern digital hearing aids that detects and suppresses this unwanted acoustic loop before it becomes audible. The hearing aid's processor continuously monitors the output signal, identifies the frequency characteristics of potential feedback, and applies a counteracting signal to cancel it. Effective feedback cancellation allows audiologists to prescribe appropriate amplification levels without the discomfort of whistling for the wearer.

This feature is particularly important for people with severe hearing loss, who require higher gain levels and are more susceptible to acoustic feedback. Without it, the amount of amplification that could be delivered safely would be limited by the risk of persistent whistling.