Why Hearing Aids Whistle - the Dreaded Feedback Problem!

Anyone who is a certain age will remember those hearing aids of the 80’s. Usually attached to a parent or grandparent, they whistled almost non-stop, usually while the poor wearer was blissfully unaware.

That will never be me, you’d think. But now it’s you! It comes to us all, and hearing aids are so much better than not hearing, inviting cognitive decline and looking completely daft, that we can put up with an odd whistle.

But, the truth is that in 2026 there is little reason to put up with feedback whistles at all. Programming, management and hopefully service has come far enough to stop it in most cases.

WHAT IS FEEDBACK?

Feedback occurs when:

1) Sound enters a microphone, is amplified and then output from a speaker

2) This ampified sound finds it’s way into the same microphone

3) The sound is amplified over and over again in a feedback loop

You can think of feedback as the equivalent of EEEEEEE on a calculator. The system is instantly overloaded, and you get nonsense coming out.

WHY DOES IT AFFECT HEARING AIDS?

In a hearing aid, you have microphones on the outside, and a speaker (also called a receiver because it receives electrical sound information) inside the ear canal. The processor in the hearing aid amplifies the incoming sound. All three components are there, within an inch or so of each other. Perfect feedback conditions! The question is not so much ‘why do I have feedback’, it’s ‘why doesn’t everyone have feedback, all the time?’!

This amplified sound is meant to hit your eardrum, causing it to vibrate and transfer the signal onward. At high volume levels though, some reflects backwards. The dome or ear mould is there to prevent that reflected sound from exiting the ear canal, but these things have holes in them for comfort and airflow, so sound can escape.

Wax in the ear canal is a major factor too, because it stops sound making it to the eardrum. Sound bounces happily off earwax - especially high frequency sound due to it’s short wavelengths. High frequencies are usually what needs the most amplification, and now were starting to see why Grandma was always whistling away.

OK, BUT WHY IS IT SUDDENLY AFFECTING MY HEARING AIDS?

Sound is leaking out of your ears, into the aids, that’s a given. One of these will apply:

1. You recently had your hearing aids reset, and now the dome or ear mould cannot cope with the new volume levels.

2. You turned the aids up on your app beyond what they are calibrated for

3. You have an increasing quantity of wax in your ear canals, or the same quantity but it’s shifted to a new place.

4. Your dome or ear mould is not correctly seated in the ear, and is not making the seal correctly.

WHAT CAN I DO?

If you have recently changed a dome, check you put the correct type back on. This must be the same dome your audiologist set the hearing aids up for.

If you have wax, clear it out (safely).

Turn the aids down in the high frequency (or just down, if that’s all you have)

Put the aids on a Comfort setting, or one that’s less sharp

If it recurring, and it’s not wax or anything you did, you need your audiologist to change your domes/earmoulds and settings to match current conditions. They should be happy to do so, as it most certainly part of their job.

END NOTES

Audiologists are constantly waging war against feedback, especially if you have a substantial hearing loss. There are different ways they can do that.

One is to precisely match the dome, the fit or the vent in your ear mould to your needs.

The other is simply turning on an aggressive feedback-manager in the software. This feedback manager works by identifying when feedback will occur, then not letting the amplified sound pass that threshold. It has made whistling less frequent, but it comes at the expense of volume.

BEWARE SHARP PRACTICE

If you have aids that sit behind the ear, your audiologist never changes your domes/moulds over the years, and your hearing ability is getting worse and worse, they are likely just making this setting more aggressive. Eventually they may say you need new hearing aids because your hearing has ‘got worse’. It may be worth getting a second opinion on this, because I have saved a lot of hearing aids from the bin by simply putting proper domes/moulds on. Obviously hearing aids will not last forever, but I am aware of plenty of audiologists who have recommended new aids when there is no need at all.