A Solution to Feedback

Feedback (also called the Larsen effect) is a common acoustic issue. In hearing aids, it occurs when the sound made by the receiver is being reabsorbed by the microphone. From there, the sound gets re-amplified, and the retroaction causes the devices to squeal.

Several different situations can cause feedback. For instance, it might happen when you’re inserting your hearing aids or when you bring something close to your ears (like when you’re hugging someone). Conventional hearing aids digital circuits systems are designed to counteract feedback by reducing amplification to eliminate the over-amplified signal. Consequently, the wearer uses hearing aids with reduced gain, thus reducing speech understanding.

One Step Ahead of the Problem

Unlike traditional anti-feedback systems that only react once the feedback is created; the Polaris platform combines two technologies: the MoreSound OptimizerTM (MSO) and the Feedback Shield. These work together to neutralize acoustic feedback before it’s even heard.

The MoreSound OptimizerTM is in the first line of defence. It breaks the feedback loop by introducing a timeand frequency-modulated signal that reduces and then quickly restores the amplification. On average, it takes just 60 milliseconds to detect and manage feedback. This patented technique has little impact on speech understanding. If the risk of feedback is only momentary, the MoreSound OptimizerTM turns off the modulation once the risk has passed. But if the risk persists, the Feedback Shield acts by reversing the phase, shifting the frequency, and, as a last resort, reducing the amplification. These innovative technologies are available in different models of hearing aids.

Other Tips to Reduce Feedback

While feedback in hearing aids isn’t harmful, the squeal can be very annoying.

You can try to solve the problem by first making sure that your hearing aid is correctly placed in your ear.

You can also consult your audioprosthetist to check for earwax buildup in your external auditory canal. Excessive earwax can increase the risk of feedback, as it prevents sound from reaching the eardrum properly.

If you hear continuous whistling, don’t hesitate to talk to your audioprosthetist for a proper adjustment.

Josée Guillemette Bilingual audiology support specialist

Charles-Édouard Basile Director of Business Development and trainer for the adult and pediatric programs