How to remove or reduce the sound of chewing food in my hearing aid?

"I hear a loud noise when I eat food, why?" This was the opening question of a patient this morning, which inspired me to write this article. If you use hearing aids and you hear a loud noise when eating food, then this article is for you.

Let's take a closer look at our outer ear.

The outer part of our ear is called the Pinna. It has an important role in collecting and directing the sound into our ear canal. The pinna, or auricle, provides a modest amount of sound amplification, primarily for frequencies around 3 kHz, with a boost of up to 15 dB, according to the University of Bristol. It also plays a crucial role in sound localisation and directing sound into the ear canal. 

The ear canal acts as a natural amplifier, primarily for higher-frequency sounds like those found in speech. It enhances these sounds by up to 10-15 decibels (dB). This amplification is due to the ear canal's resonant properties, which are determined by its length. 

When you chew food, the movement of the food in your mouth and the movement of your jaw and associated muscles create sound. This sound does an echo and is amplified in your ear canal. For people without hearing aids, this noise exists from the ear canal, but for people with hearing aids with a closed or power fitting dome, this noise can be loud. People without hearing aids can simulate this by using their thumb to close their ear canal while they are eating food.

How to reduce or remove the sound of chewing food in my hearing aid?

This issue is more annoying for people with hearing loss in low frequencies. If a patient has moderate to severe hearing loss in the low and mid frequencies, then it is very likely that your audiologist would suggest a closed or power dome for fitting your hearing aids. To manage the sound of chewing food when using hearing aids, I try fitting the patient with closed-vented domes. If the feedback test does not pass and the patient needs to be fitted with power domes, then I would recommend considering micromoulds.

Besides better retention in the ear canal, a micromould helps present the amplified sound deeper and closer to the eardrum, while through a small vent, it allows excessively low frequencies to escape from the ear canal. The result is a more natural sound. It also minimises the occlusion effect for the patient.

Please check this article on micromoulds and when one should consider them for fitting hearing aids.

References

• Bristol University website

• The external ear, Neuroscience, 2nd edition

• Do I need micro earmoulds?