How do hearing aids work? Are they just blasting what they hear directly into the ear potentially causing more damage?
In: Biology
I have wore hearing aids for the last 15-16 years (since I was 16, 31 now). A lot of people have explained this a lot better than I have, but wanted to chime in anyway.
Like others have said, hearing aids just don’t make sounds louder. Little microphones are constantly going on and off and making the sound…sound right. Example, high pitched sounds are really hard for me to hear. My current pair of hearing aids have a program that take those high pitched sounds and bring them to an octave I can hear. An audiologist tests my hearing, and programs the hearing aids to my level of high pitched loss. Same goes for lower, bass sounds.
Probably not the place of this, but I really need to get it off my chest: I firmly believe those who buy an OTC hearing aid are going to have a bad time. “Professional” hearing aids cost a lot (don’t get me started on that), but they are custom programmed and fitted for me, and not my mom.
Am hearing aid user.
Good hearing aids amplify high, low, and in-between sounds exactly as much as they need to make a person’s hearing normal. I have hearing loss that effects high sounds, so my hearing aids pump up mostly high pitched sounds that mix with real sound.
Most hearing aids max out at certain volumes. Mine stop at 107 decibels, which is around when sound can hurt someone’s hearing. If someone needs sound to be louder than that to correct their hearing, they need to get something other than hearing aids (cochlear implant). If real sound is louder than 107 decibels, my hearing aids do nothing. If real sound is 106 decibels, but my hearing aids are supposed to add 10, they only add 1, because they won’t go over 107.
This is good, because only one part of my hearing is broken. There are four steps to hearing: the ear drum, the ear bones, the hearing nerves, and the listening brain. My damage is in the hearing nerves. If sound is too loud, I can still damage my ear bones, and I have. I used to think “I’m broken, so I don’t need earplugs!” and didn’t wear them when I should have, and hurt my ear bones, which made my hearing worse.
Have you ever seen a professional musician mixing board, with all the levers and nobs? A good hearing aid has those same nobs, but all computerized. A good hearing aid doctor is called an audiologist, and will tune a hearing aid to be perfect for someone’s hearing damage.
There aren’t that many laws in the United States about hearing aids, so you don’t have to be an audiologist to sell them, and you can sell bad hearing aids. There are places where non-doctors sell hearing aids that just blast everything really loudly. They are not good, but they are also cheap. I would not recommend then.
For starters, I work as an Engineer for one of the largest hearing aid manufacturers in the world, although in the Quality & Regulatory Affairs side of things, so I’m not as well-versed as a member of R&D would be.
I’ll cover the second point first, Power and Super Power hearing aids intended for those who have severe and profound hearing loss can be amplified to the extent where they would cause damage to those without hearing loss or with moderate loss.
As such, any hearing aid should always be programmed by a hearing care professional (audiologists and hearing aid dispensers in the UK) prior to issue, as they ensure that the hearing aid is programmed on safe settings. DO NOT buy hearing aids via mail order or over the internet, as the face-to-face consultation and fine tuning is essential for ensuring safety and maximising performance/troubleshooting.
Effectively, your hearing doesn’t get damaged because the only time a hearing aid should put out potentially damaging volumes is at frequencies where the damage has already been done.
As part of your hearing aid fitting the HCP (Hearing Care Professional) will perform a hearing test, which produces an audiogram detailing your hearing loss at various frequencies, typically up to 8 kHz. This audiogram is then used to determine which hearing aids (if any) are suitable for your hearing loss – typically the less severe your hearing loss, the more options you have as the smaller, custom instruments typically produce less powerful outputs.
If you are getting an off-the-shelf hearing aid, either called a behind-the-ear (BTE) or receiver in-the-ear/canal (RITE/RIC) with no custom ear mould this can be fitted to you the same day as your test, but if a custom hearing aid or mould is chosen there’s usually a 1-3 week turnaround for the aid/mould to be manufactured.
When the finished product is available the HCP will program the device to suit your hearing loss – in broad terms it will amplify frequencies which you don’t hear well and leave frequencies which you can hear un-amplified, which is why another person’s hearing aid won’t work for you. Newer hearing aids also perform frequency transposition, where high frequencies (such as the letter “S”) that patients can’t hear well, or at all, are changed to a lower frequency to allow them to hear it.
In crowded rooms basic hearing aids in a pair will also evaluate the sound that you are hearing to allow you to focus on a single person. This is typically done by determining if both hearing aids are receiving speech at the same volume, as that indicates that you are facing the source of the speech. When this occurs the rear microphones are made quieter to allow you to focus on the person you are facing.
More advanced hearing aids will scan the room hundreds of times per second to allow speech from all around you to be cleaned up and give a more realistic experience in a crowded room.
On top of that you have bluetooth functionality, connectivity to phones, TVs, mobiles, FM adapters (primarily in schools), but they don’t have any real effect on the basic functionality of the aid.
Please note, this is a very simple take on a really complicated subject, so there may be sections which aren’t 100% correct, but are worded in a way to make it easy to understand.
There are different kinds of hearing aids. The specific type depends on the damage to the ear.
If you just “hear bad” specialized amplifiers can be used to alter the volume and frequency range to improve your hearing.
If some parts of the ear are damaged a cochlear implant can be used. This is basically a microphone with some electronics that is direct hooked up to the nerves in the inner ear and stimulates them to allow hearing.
Old ones did just amplify everything regardless or frequency or decibels so that far off siren is just as loud as your gf telling you to get off the couch. New ones are really nuanced and high tech so they can tell what to filter and what no to.
The tech now is pretty amazing. My husband has a set from the VA as a treatment for his tinnitus. He was in aviation fuels on an aircraft carrier during his service. They are specifically tuned to add white noise to cancel out what he hears as alternatively buzzing/ringing. Amazing. He can also answer his phone, stream music, watch movies, etc.
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They do increase the volume of what they hear, but only up to a safe limit, so they don’t damage the ear. These limits are set by the fitter based on a hearing test.
There’s lots of other processing that they do to avoid blasting everything, and only what the hearer wants to hear. There is a LOT of research that goes into how exactly to do this.
I have hearing aids, generally no, they don’t cause any more damage and my hearing is at the “severe” level (before profound/deafness.) hearing aids work by picking up sound in the microphones usually located on the rear and top they send the sound through the tube and into the ear. They also use batteries and I think some are actually rechargeable but mine are not. But I will say that they do blast anything they hear into the ear unless you alter them at a doctors not to, but the result of filtering out sounds to get voices better will lead to a shitton of jumpscares. As a result, hearing aids mostly blast everything they pick up into the ear without discrimination.
Imagine there are strings of different length inside the ear that vibrate to a well defined frequency and transform the signal to a nerve impulse that the brain interprets as sound.
When those strings snap we stop hearing sounds in that frequency, a hearing aid just “translates” those missing frequencies into ones that the person in question can hear
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