Do hearing aids damage ears? Is the helping hurting in the long run?

Posted by bobbyboomer @bobbyboomer, Mon, Jul 15 9:42am

I had this discussion on the HLAA forum and got no satisfactory answer. The HLAA forum is pretty dead and on it's way out so I didn't get but one or two responses and they weren't conclusive. Also it is my fault because I don't think I explained myself clearly.

Please understand, I'm not trolling, I really want to know. If my logic is sound, I will only wear my aids when I need to instead of all day. I can't get along without them.

Let me divulge my logic (or lack of it):

1) I know that the sound level of 85dba ("A" weighted, slow response) for 8 hours per day permanently damages hearing. The DB scale is logarithmic function, each 3db is double the power of the one before. So at 91dbdba 2 hours of exposure damages permanently, at 100dba it's only 15 minutes, at 110dba it's mere seconds and at 120dba it's instant permanent damage. Logarithms are comparative ratios, adding the a suffix (dba) is referencing it against a standard, and is what all hearing tests use — db is a ratio and dba is a definite value.

2) Hearing aids amplify the frequencies you cannot hear as a reverse curve to your hearing loss audiogram

3) Say you have a 70 db loss in hearing at 3Khz (3,000 cycles per second), that means at 71 dba in a quiet hearing booth you can barely hear the faintest whisper of a 3khz tone. And like many of us, say your lower frequency hearing is either zero or around 6 dba. (note: most consonants are in the 2-4 khz range so this is where we understand speech)

4) Now say you are in a room that conversation level is around 75 dba, you will need about 75 db of the consonants to understand what the person across the table is saying to you. (Note: I have several sound level meters and 75db in a restaurant is average for one without loud background music.)

5) Since your hearing loss is at -70db, there is already 75dba of conversation in the room how high does your hearing aid have to amplify the 3khz sounds?

6) Do you have to take the 70db loss, add it to the 75dba conversation level in the room and amplify to an ear damaging 145dba? Remember, adding 70dba is your tiniest, softest, perception at the frequency in a quiet soundproof booth. So it seems 70dba wouldn't be enough. Hearing a whisper of a consonant in a 75dba room seems to me to be worthless.

So it seems to me that amplifying the ambient noise of the room above 85dba could slowly erode your hearing so you will need stronger and stronger hearing aids, which amply more and damage more, which means you will need stronger and stronger hearing aids, damaging more and more. etc. (feedback loop)

Or am I missing something?

If my thinking is faulty, please explain in detail and tell me why my logic is not logical.

Thanks,
Bob

Thanks!

On first scan, this looks like the kind of information I'm looking for. I'll dive into that more deeply as soon as I'm done in this forum.

Bob

REPLY
@bobbyboomer

I'm still searching and asking questions, but so far no definitive answers.

I do know that my old ReSound Air aids had the potential to harm ears with a max of 100dba. As far as I'm concerned, that's no difference from running an iPod at 100dba.

I hate to think what is providing me a way not to be so isolated from other people is causing damage that in the long run will make me even more isolated from other people.

So like I said earlier, until I get an answer, I'm staying away from noisy environments.

Bob

Jump to this post

@bobbyboomer, to help you and others in your search for answers, I took your question to Dr. Zapala, audiologist and Division Chair of Audiology at Mayo Clinic in Florida. This is what he has to add. (Get comfortable. It's a long and comprehensive response.)

++++
From Dr. Zapala

Bobbyboomer asks a very good question: Can hearing aids cause more hearing loss. The short answer is “no” as long as the hearing aid is fit correctly. If the hearing aid is fit correctly, the computer inside the hearing aid will be programmed to automatically limit the sound level entering your ear so that it is safe and more or less comfortable. This is why audiologists make careful measurements with tools like probe mic systems (where a tiny microphone attached to a noodle like tube is inserted into your ear canal during the hearing aid fitting process). Probe mic systems record the sound level in your ear canal to fine tune the hearing aid program to make sounds as comfortable as possible.

The longer answer is a little complicated, but it is just so amazing what are ears do. I am thankful every day that my own hearing loss is manageable (so far).

There are basically two types of hearing loss: conductive and sensorineural. Conductive hearing loss happens when sound does not get to the cochlea normally. Problems in the ear canal, eardrum, middle ear bones (malleus, incus and stapes) or the temporal bone can cause hearing loss that is often surgically or medically correctable. For these types of hearing loss, once sound enters the inner ear, it is processed normally. So if a wax plug causes a 20 dB hearing loss, an amplifier that increases the intensity of a sound by 20 dB will result in clear normal perception of sound. By analogy, this is like having near or far vision. With the right lenses, functional vision can be more or less restored.

Sensorineural hearing loss is very different. It is analogous to macular degeneration. The inner ear or “cochlea” is a snail shell shaped tunnel that is fluid filled. Snaking through the tunnel, winding from the opening, all the way to the coiled end of the cochlea is a membrane. Think of a nylon stocking inserted all the way to the tip of the snail shell. Inside the nylon stocking is a different type of fluid. Part of the nylon stocking is attached to the bony canal along its length so that it can move. When acoustic energy enters the cochlea, a pressure wave is created that travels along the length of the stocking. The stocking is structured so that different parts of it will move to sounds with different frequencies. High frequency sounds will stimulate the part of the stocking near the middle ear. Low frequency sounds travel all the way to the tip of the coil and stimulate that part of the stocking. This is how the ear begins to create pitch and tone sensations. Soft sounds make the stocking move very little. More intense sounds induce larger movement. This is how loudness begins to be created.

On the surface of the stocking (OKAY, it is called the Scala media) there are several tiny specialized cells, haircells. Some haircells (inner hair cells) have several nerves connected to them that travel to the brain. When the Scala media moves a tiny bit, as in response to a soft sound, only a few of the connected nerves are stimulated. When the Scala media moves a lot, as in response to a loud sound, most of the nerves are stimulated. This is another way sound intensity is coded into loudness sensations.

If there are inner hair cells, there must be outer hair cells. Outer hair cells do something very different. If a sound makes the Scala media move at its tuned frequency, these cells act like springs, changing the way the stocking moves. For soft sounds, the outer hair cells amplify the Scala media movement, so that the inner hair cells get stimulated to very, very soft sounds. When sounds are more intense, they stop adjacent areas of the Scala media from moving so much, improving pitch perception. All of this requires energy. In normal hearing ears, a lot of energy is used to detect soft sounds and develop refined sensations of pitch and loudness.

So when these structures or processes are damaged, hearing loss occurs. But it is very different from conductive hearing loss. Three and sometimes four things happen. First, the ear losses the ability to detect soft sounds in the damaged region (hearing loss). Second, the ear can’t encode loudness the same way. Soft sounds may not be heard, but loud sounds can become unbearably loud. Third, the ability to resolve frequency diminishes. It becomes harder to distinguish between similar sounds –sounds get distorted. And finally, damaged cells and nerves may begin to fire off on their own, causing the sensation of tinnitus. (BTW, tinnitus can be caused by conductive hearing loss as well – through a different process).

Hearing aids have little computers that can be programmed to make soft sounds louder, and loud sounds softer. They can attempt to only amplify sounds coming from a specific direction or only amplify sounds that might be speech. They are really amazing devices. But sadly, they cannot, at this point, overcome all of the distortions that occur with sensorineural hearing loss. There is some good news though…. But first a little math.

If a person has a 40 dB sensorineural hearing loss, they will not like 40 dB of amplification. Loud sounds become too loud in sensorineural hearing loss. So a well programmed hearing aid will try to shoehorn sounds to fit in the hearing range where they will be perceived to be comfortable and speech understanding will be optimal. So maybe 30 dB of amplification to soft sounds for example, 10 dB of amplification for moderately loud sounds, and actually reduce the level of very loud sounds. …And the hearing aid will do this for a multitude of frequencies because in sensorineural hearing loss, pitch and loudness perception changes with frequency. I say “shoehorn sounds” to be comfortable and speech understanding will be optimal, but this is not always possible. Sometimes there is a tradeoff and the audiologist and the person with hearing difficulties will need to decide which is more important. Sensorineural hearing loss is challenging!

So the good news… You don’t really see what you think you see. Hold your thumb up in front of you and look at the far wall. How many thumbs do you see? Answer: 2. Look at your thumb, how many walls do you see? Answer: 2. Over the years, your brain has learned to interpret the two images striking your eyes as a world with depth.

You don’t really hear what your ears hear. 🙂 Your brain learns to interpret the sounds that strike your ear drums into a rich three dimensional world. That is why many people do not recognize that they have hearing loss. The brain adapts – within certain limits. So if you are having trouble adjusting to hearing aids, be patient. To some extent the brain can adapt. When that is not enough, using assistive technologies such as remote microphones and loops can help. Cochlear implants are also always improving and can help in more severe cases of hearing loss.

The really good news is that one day, we will very likely be able to grow new haircells and nerves. …or maybe we will create a technology to replace them. I did not think I would see that in my life time, and there is still a lot of work to do. But I am amazed at what has been accomplished. Keep the faith!

REPLY

Thanks Colleen for taking this forward. 🙂 Many of us have a strong desire to learn as much as we can and it's wonderful that experts are willing to share their knowledge with us. This discussion is helping me better explain this question when I am asked by those that are ready to improve their hearing or just are curious.

REPLY
@colleenyoung

@bobbyboomer, to help you and others in your search for answers, I took your question to Dr. Zapala, audiologist and Division Chair of Audiology at Mayo Clinic in Florida. This is what he has to add. (Get comfortable. It's a long and comprehensive response.)

++++
From Dr. Zapala

Bobbyboomer asks a very good question: Can hearing aids cause more hearing loss. The short answer is “no” as long as the hearing aid is fit correctly. If the hearing aid is fit correctly, the computer inside the hearing aid will be programmed to automatically limit the sound level entering your ear so that it is safe and more or less comfortable. This is why audiologists make careful measurements with tools like probe mic systems (where a tiny microphone attached to a noodle like tube is inserted into your ear canal during the hearing aid fitting process). Probe mic systems record the sound level in your ear canal to fine tune the hearing aid program to make sounds as comfortable as possible.

The longer answer is a little complicated, but it is just so amazing what are ears do. I am thankful every day that my own hearing loss is manageable (so far).

There are basically two types of hearing loss: conductive and sensorineural. Conductive hearing loss happens when sound does not get to the cochlea normally. Problems in the ear canal, eardrum, middle ear bones (malleus, incus and stapes) or the temporal bone can cause hearing loss that is often surgically or medically correctable. For these types of hearing loss, once sound enters the inner ear, it is processed normally. So if a wax plug causes a 20 dB hearing loss, an amplifier that increases the intensity of a sound by 20 dB will result in clear normal perception of sound. By analogy, this is like having near or far vision. With the right lenses, functional vision can be more or less restored.

Sensorineural hearing loss is very different. It is analogous to macular degeneration. The inner ear or “cochlea” is a snail shell shaped tunnel that is fluid filled. Snaking through the tunnel, winding from the opening, all the way to the coiled end of the cochlea is a membrane. Think of a nylon stocking inserted all the way to the tip of the snail shell. Inside the nylon stocking is a different type of fluid. Part of the nylon stocking is attached to the bony canal along its length so that it can move. When acoustic energy enters the cochlea, a pressure wave is created that travels along the length of the stocking. The stocking is structured so that different parts of it will move to sounds with different frequencies. High frequency sounds will stimulate the part of the stocking near the middle ear. Low frequency sounds travel all the way to the tip of the coil and stimulate that part of the stocking. This is how the ear begins to create pitch and tone sensations. Soft sounds make the stocking move very little. More intense sounds induce larger movement. This is how loudness begins to be created.

On the surface of the stocking (OKAY, it is called the Scala media) there are several tiny specialized cells, haircells. Some haircells (inner hair cells) have several nerves connected to them that travel to the brain. When the Scala media moves a tiny bit, as in response to a soft sound, only a few of the connected nerves are stimulated. When the Scala media moves a lot, as in response to a loud sound, most of the nerves are stimulated. This is another way sound intensity is coded into loudness sensations.

If there are inner hair cells, there must be outer hair cells. Outer hair cells do something very different. If a sound makes the Scala media move at its tuned frequency, these cells act like springs, changing the way the stocking moves. For soft sounds, the outer hair cells amplify the Scala media movement, so that the inner hair cells get stimulated to very, very soft sounds. When sounds are more intense, they stop adjacent areas of the Scala media from moving so much, improving pitch perception. All of this requires energy. In normal hearing ears, a lot of energy is used to detect soft sounds and develop refined sensations of pitch and loudness.

So when these structures or processes are damaged, hearing loss occurs. But it is very different from conductive hearing loss. Three and sometimes four things happen. First, the ear losses the ability to detect soft sounds in the damaged region (hearing loss). Second, the ear can’t encode loudness the same way. Soft sounds may not be heard, but loud sounds can become unbearably loud. Third, the ability to resolve frequency diminishes. It becomes harder to distinguish between similar sounds –sounds get distorted. And finally, damaged cells and nerves may begin to fire off on their own, causing the sensation of tinnitus. (BTW, tinnitus can be caused by conductive hearing loss as well – through a different process).

Hearing aids have little computers that can be programmed to make soft sounds louder, and loud sounds softer. They can attempt to only amplify sounds coming from a specific direction or only amplify sounds that might be speech. They are really amazing devices. But sadly, they cannot, at this point, overcome all of the distortions that occur with sensorineural hearing loss. There is some good news though…. But first a little math.

If a person has a 40 dB sensorineural hearing loss, they will not like 40 dB of amplification. Loud sounds become too loud in sensorineural hearing loss. So a well programmed hearing aid will try to shoehorn sounds to fit in the hearing range where they will be perceived to be comfortable and speech understanding will be optimal. So maybe 30 dB of amplification to soft sounds for example, 10 dB of amplification for moderately loud sounds, and actually reduce the level of very loud sounds. …And the hearing aid will do this for a multitude of frequencies because in sensorineural hearing loss, pitch and loudness perception changes with frequency. I say “shoehorn sounds” to be comfortable and speech understanding will be optimal, but this is not always possible. Sometimes there is a tradeoff and the audiologist and the person with hearing difficulties will need to decide which is more important. Sensorineural hearing loss is challenging!

So the good news… You don’t really see what you think you see. Hold your thumb up in front of you and look at the far wall. How many thumbs do you see? Answer: 2. Look at your thumb, how many walls do you see? Answer: 2. Over the years, your brain has learned to interpret the two images striking your eyes as a world with depth.

You don’t really hear what your ears hear. 🙂 Your brain learns to interpret the sounds that strike your ear drums into a rich three dimensional world. That is why many people do not recognize that they have hearing loss. The brain adapts – within certain limits. So if you are having trouble adjusting to hearing aids, be patient. To some extent the brain can adapt. When that is not enough, using assistive technologies such as remote microphones and loops can help. Cochlear implants are also always improving and can help in more severe cases of hearing loss.

The really good news is that one day, we will very likely be able to grow new haircells and nerves. …or maybe we will create a technology to replace them. I did not think I would see that in my life time, and there is still a lot of work to do. But I am amazed at what has been accomplished. Keep the faith!

Jump to this post

Colleen, Dr. Zapala mentions how that probe mics are inserted into the ear during audiologic testing. I assume that this is the same as what's called Real Ear Measurment (REM). My understanding is that only a small portion of audiologists perform this test and thus, the fitting is not as ideal as it could be.
Tony

REPLY

Mine did not.

REPLY

Thanks, Colleen!

REPLY
@tonyinmi

Colleen, Dr. Zapala mentions how that probe mics are inserted into the ear during audiologic testing. I assume that this is the same as what's called Real Ear Measurment (REM). My understanding is that only a small portion of audiologists perform this test and thus, the fitting is not as ideal as it could be.
Tony

Jump to this post

Yes, something less then 40% follow the American Academy of Audiology best practices, probably far less since, I imagine that a lot of those that don't also don't fill out surveys. For the purposes of this thread that doesn't mater so much as the setup that comes from the manufacturer will be safe, but it is probably one of the big reasons for dissatisfaction with hearing aids in general, i saw a study once that showed following the practices was associated with a significantly lower rate of returns.

REPLY

The majority of Hearing Health Professionals have a very long way to go to provide the services and support we need. The Hearing Aid Manufacturing Companies are frustrated to. They invest a lot to teach them best practices but many just don't adopt them. The provide educational conferences, one-on-one training, periodic F2F visits and education. I only Audiologist I recommend to anyone in our area, follows best practices and is doing very well. It's good for business as they get a lot of referrals. This practice also has a monthly 2-hour support group / educational meeting (except summers) that is open to the public. This is very well received and many people come back every month.

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