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On Hearing and Sensory Adaptation
To all. I wish to correct some comments I previously made and explain hearing physiology correctly to avoid any misconceptions that I may have created
I have previously talked about "warming up your ears" in the context of volume levels and how our hearing adapts to loud volumes. This is also key in avoiding long term and permanent hearing damage.
In our middle ears sound is transferred from the tympanic membrane (ear drum) to the inner ear through three bones the malleus, incus and stapes (hammer, anvil and stirrup). Our nervous system has two ways of damping vibration traveling from the TM through the three bones to the inner ear. These operate reflexively and are animated by two different muscles, the Tensor Tympani and the smallest skeletal muscle in the body the Stapedius. The TT attaches to the malleus that itself is attached to the middle ear side of the TM. When a loud low frequency sound occurs the TT tightens pulling back on the TT stiffening it. It takes 40 ms for this reflex to occur which is fast enough for a thunder clap but not fast enough to keep something like a gun shot from damaging the ear. This is innervated via the Trigeminal nerve. The stapedius attaches to the stapes and when it contracts it pulls the stapes away from the inner ear decreasing the transmission of all frequencies something like 15 dB. It is a little slower than the TT reflex depending on the intensity of the sound taking up to 150 ms not minutes as I previously described. It contracts at anywhere between 80 and 100 dB and does protect your ears to some extent from continuous loud noise but again not lone impulse noise. This is innervated by the Facial or 7th cranial nerve which is the same nerve affected by Bell's palsy and indeed people with Bell's frequently suffer from hyperacusis, sounds are too loud and they shy away from noisy situations.
There is another mechanism involved that does take up to several minutes to become active and that is sensory adaptation. If you are listening to loud music that at first makes you wince, after a few minutes it will not seem near as loud. This is the other part of "warming up your ears." However it is a potentially dangerous event because it makes one more tolerant of noise that might damage your ears. The Stapedius or auditory reflex is protective. Sensory adaptation is not. I keep a sound pressure meter handy so I know what I am listening too and try not to listen routinely over 95 dB.
95 dB is supposed to be tolerable for 45 minutes. The problem is that there is an element of genetic susceptibility which is essentially an unknown. If both your parents were deaf by age 70 and were not engaged in loud professions I would worry and be more careful. By the time your ears start ringing or your hearing drops off for hours after a concert damage has already been done. There seems to be a consensus that ear buds and headphones cause more damage. I do not use them for listening to music. I prefer feeling the music as if I were at a concert. If you "warm up your ears," boost your low bass a bit you can feel like you are at a concert at levels that are tolerable (95dB) for one full album. The question I have always had is, if it is OK to run 95 dB for 45 minutes how long do you have to recover before you do it again? I have not been able to find the answer to that question.
In medicine we have a tendency to over do our recommendations for liability reasons. As an example we use to do PAP tests on woman yearly. That has now changed to every 5 years in healthy woman. As more data came in we learned we could safely back off. My generation was the first that routinely attended very loud concerts and we are now getting to the age where our hearing should start to sour. Hopefully more studies will be done on us to determine what this kind of hearing exposure does and what is really tolerable. I do comprehensive audiology in my office. My general feeling is that there does not seem to be a lot of difference between concert goers and home bodies. I always take hearing protection to concerts just in case.
I find that warming up my ears by starting at 80 dB and working my way up makes me more comfortable at volume and allows me to find that "right" volume on the way up. It the music sounds right at 87 dB like a lot of classical music, I will stop there. On the way up your stapedius tightens and gives you another safe 15 dB. As the music gets louder the frequency response you perceive changes which is why each performance has a volume it sounds best at.
Sorry if I created any confusion.
I have previously talked about "warming up your ears" in the context of volume levels and how our hearing adapts to loud volumes. This is also key in avoiding long term and permanent hearing damage.
In our middle ears sound is transferred from the tympanic membrane (ear drum) to the inner ear through three bones the malleus, incus and stapes (hammer, anvil and stirrup). Our nervous system has two ways of damping vibration traveling from the TM through the three bones to the inner ear. These operate reflexively and are animated by two different muscles, the Tensor Tympani and the smallest skeletal muscle in the body the Stapedius. The TT attaches to the malleus that itself is attached to the middle ear side of the TM. When a loud low frequency sound occurs the TT tightens pulling back on the TT stiffening it. It takes 40 ms for this reflex to occur which is fast enough for a thunder clap but not fast enough to keep something like a gun shot from damaging the ear. This is innervated via the Trigeminal nerve. The stapedius attaches to the stapes and when it contracts it pulls the stapes away from the inner ear decreasing the transmission of all frequencies something like 15 dB. It is a little slower than the TT reflex depending on the intensity of the sound taking up to 150 ms not minutes as I previously described. It contracts at anywhere between 80 and 100 dB and does protect your ears to some extent from continuous loud noise but again not lone impulse noise. This is innervated by the Facial or 7th cranial nerve which is the same nerve affected by Bell's palsy and indeed people with Bell's frequently suffer from hyperacusis, sounds are too loud and they shy away from noisy situations.
There is another mechanism involved that does take up to several minutes to become active and that is sensory adaptation. If you are listening to loud music that at first makes you wince, after a few minutes it will not seem near as loud. This is the other part of "warming up your ears." However it is a potentially dangerous event because it makes one more tolerant of noise that might damage your ears. The Stapedius or auditory reflex is protective. Sensory adaptation is not. I keep a sound pressure meter handy so I know what I am listening too and try not to listen routinely over 95 dB.
95 dB is supposed to be tolerable for 45 minutes. The problem is that there is an element of genetic susceptibility which is essentially an unknown. If both your parents were deaf by age 70 and were not engaged in loud professions I would worry and be more careful. By the time your ears start ringing or your hearing drops off for hours after a concert damage has already been done. There seems to be a consensus that ear buds and headphones cause more damage. I do not use them for listening to music. I prefer feeling the music as if I were at a concert. If you "warm up your ears," boost your low bass a bit you can feel like you are at a concert at levels that are tolerable (95dB) for one full album. The question I have always had is, if it is OK to run 95 dB for 45 minutes how long do you have to recover before you do it again? I have not been able to find the answer to that question.
In medicine we have a tendency to over do our recommendations for liability reasons. As an example we use to do PAP tests on woman yearly. That has now changed to every 5 years in healthy woman. As more data came in we learned we could safely back off. My generation was the first that routinely attended very loud concerts and we are now getting to the age where our hearing should start to sour. Hopefully more studies will be done on us to determine what this kind of hearing exposure does and what is really tolerable. I do comprehensive audiology in my office. My general feeling is that there does not seem to be a lot of difference between concert goers and home bodies. I always take hearing protection to concerts just in case.
I find that warming up my ears by starting at 80 dB and working my way up makes me more comfortable at volume and allows me to find that "right" volume on the way up. It the music sounds right at 87 dB like a lot of classical music, I will stop there. On the way up your stapedius tightens and gives you another safe 15 dB. As the music gets louder the frequency response you perceive changes which is why each performance has a volume it sounds best at.
Sorry if I created any confusion.
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There is an uncanny resemblance to high end photography. Uncanny. https://www.kenrockwell.com/tech/7.htm The lowest bottom level in particular. (There is an even lower level, Level Zero. Read these descriptions- if you dare.) |
@mijostyn I forgot to mention. Etymotic, the company that makes Hi fidelity ear buds makes tunes ear plugs for musicians that dampen the volume without changing frequency response. Great product. Great suggestion. We have been using Etymotic High Fidelity musicians’ ear plugs for many years when attending rock concerts. As you say, they attenuate volume without affecting frequency balance (~20dB attenuation). Nice original post as well. |