Whistling sound from a hearing aid is also known as Feedback. Why do hearing aids whistle? What exactly happens with hearing aid whistle and feedback is there is a pathway for amplified sounds to leak out of the ear, and the leaking sound got picked up by the hearing aid microphones repeatedly and therefore resulting in a sharp and harsh whistling sound.
This kind of sound can seriously affect the hearing experience of the hearing aid users. Not only is it harsh and annoying, but it also makes speech understanding ability difficult.
Most digital hearing aids nowadays have automatic feedback cancelation features. Therefore, if feedback still occurs after fitting, it is most likely due to one of the following reasons.
There are two types of hearing feedback: internal and external;
Internal feedback is uncommon and is usually the result of a break, crush, or damage to the hearing aid. Internal feedback means the whistling noise is coming from the internal part of the hearing aid itself. In this case, you need to return the hearing aid to the manufacturer for repair.
The whistling that many hearing aid users often complain about is often caused by external factors, in other words, whistling noise that’s not coming from the hearing aid itself.
External whistling occurs when the hearing aid microphones unexpectedly collect sounds from the gap(s) that are created between the ear canal and the hearing aid.
(1) The hearing aid ear mold is too loose or is not worn properly
Suppose you are using a behind-the-ear hearing aid and wearing the ear mold incorrectly. In this case, a gap or gaps will be formed between the ear mold and the ear canal, amplified sounds leak out of the ear through the gap(s) and resulting in whistling. In this case, the necessary thing that you need to do is to wear the ear mold correctly. Ensure that you insert the ear mold and hearing aid entirely and in the correct position. By doing so, the whistling should stop.
If it is a custom hearing aid, you will not likely wear it improperly under normal circumstances, but there may be various reasons to cause feedback. The initial ear mold impression was not done well, which may cause the custom hearing aid not fully match the ear canal in size and / or shape, resulting in the ear mold fitting loosely in the ear. In this case, you need to return the ear mold to the manufacturer and have the manufacturer remake the ear mold. If necessary, a new ear mold impression is needed to be remade by an audiologist.
(2) The hearing aid vent hole is too big
A hearing aid could have a relatively large vent hole to reduce occlusion effect, by excreting the excess sound energy through the vent hole
However, if the patient’s hearing loss becomes more severe, and it requires the hearing aids to provide more amplification, but the size of the vent hole is still the same; the excessive amplified sounds can leak out of the patient’s ear through the vent hole, and therefore resulting in feedback or whistling.
(3) The ear hook or the sound tube breaks
The sound tube may break over time if one uses behind-the-ear style hearing aids. There may even be earwax or moisture in the sound tube, resulting in feedback.
In addition, the ear hook itself may break or it is not properly connected to the hearing aid, which results in sounds leaking out and get pick up repeatedly by the hearing aid microphones, and resulting in feedback. In this kind of situation, replacing the broken ear hook and / or tubing is the appropriate step to take.
(4) Too much earwax
Sometimes excessive earwax can also cause feedback. This is because due to the excessive amount of wax, the hearing aid is unable to create a tight seal with the ear canal, instead it creates gaps, and sounds can leak out from those gaps.
Earwax in the ear canal can also cause the amplified sounds that entered the ear to bounce back out of the ear. Sounds that bounced back out of the ear got picked up by the microphones repeatedly and therefore cause whistling. This problem can be solved by cleaning out earwax by an audiologist or an ENT doctor.
When hearing aids whistle, you don't need to panic. Sometimes the solution is as simple as a change to a different size of earplugs or modifications needed to be done to the ear molds. You need to contact your hearing health professional as soon as possible to inform them of your specific situation, and your hearing health specialist will give you their appropriate responses based on their judgments, and provide you with the correct treatments.