– how do hearing aids work?


My dad and a colleague both wear hearing aids and they both complain it’s harder to hear because everything gets turned up. I don’t understand what they mean, wouldn’t it all increase in volume relative to it’s initial volume level?

Side note – my dad just started wearing a hearing aid but my colleague has been wearing one for over 20 yrs so I don’t agree that the reason is not being used to the hearing aid.

In: Technology

I am not an expert so would be happy to see an expert chime in, but I can speak as a user of hearing aids.

I think cheaper hearing aid models do increase the volume of everything. This isn’t helpful as sounds can “blend” together for hearing-impaired individuals.

More expensive models take the results of your specific hearing test and identify only the pitch ranges that need to be boosted, and increase the volume there. So if you can normally hear bass tones but can’t hear higher-pitches, they would only boost the high-pitches.

No solution yet is perfect though and the extent of hearing loss is highly individual, so they very well might be experiencing an overwhelming garbling of sounds even with decent hearing aids. I definitely shy away from any place with background noise if I want to be able to hold a conversation.

Hearing and hearing loss is quite complex. Hearings aids are not capable of restoring all the properties of the healthy cochlea, but the basic volume compensation goes approximately like this:

Our hearing is seperated into frequency bands. You can imagine this with a xylophone, for true eli5. When you lose hearing, your thresholds generally decline in the higher frequency ranges. So you cannot hear the short xylophone parts that well. In the frequency bands where you have hearing loss you need higher volumes to be able to hear it. For example you have to smack harder on the short parts of the xylophone to produce the same volume as a light smack on the long one. Hearing aids follow this frequency band approach and amplify incoming sounds per frequency band, based on your individual auditory thresholds. So, again assuming high frequency hearing loss, it leaves the long xylophone sticks unaltered, but strongly amplifies the short xylophone stick.

In short:
Without hearing aid and gently tapping a xylophone

Ding ding ding ding…….

With hearing aid and gently tapping a xylophone

Ding ding ding ding ding ding


As I mentioned hearing loss is complex and covers far more than just increased thresholds. For example the frequency specificity goes way down in the hearing impaired system. Going back to the xylophone, in the normal hearing system each part activates a single frequency band, but in the impaired system multiple parts of the xylophone might activate the same frequency band in the cochlea. Because of the way loudness perception works, this means that when you have multiple xylophone sticks activating the same band, it appears louder.

Oh oh! I’m actually a licensed hearing instrument specialist.

In the simples way possible, hearing aids amplify sound to levels that the wearer can still hear. Now, not all sound is equal (like all the different keys on a piano), so when we test for hearing loss we’re measuring at different frequencies where the person is just barely able to hear. More often than not, a person with hearing loss will not hear all of these tones equally. The hearing aid is programmed based on this measurement and amplifies these ranges accordingly and possibly further tweaked based on the wearer’s feedback.