I was just reading another thread where posters were comparing the power of their reggae music speakers. Wondering about bass damage to hearing, I found an older thread about lounge music but thought I'd bring the unresolved issues to this location.
I have long wondered about damage to hearing from one-note reggae music, dance clubs, those aficionados in cars with booming sound systems, and, of course, my own systems too.
The usual hearing-damage standards (which are not based on compelling evidence) are stated as general SPL, and I believe dBA. Should a loud one-note bass be assessed for risk the same way? Does dBA go that low?
Odd, when your hearing deteriorates, the low frequencies are barely affected. Does that mean low frequency sound doesn't harm your hearing much?
Also, I have also wondered if your hearing really is protected by having a very loud "noise cancelling" signal counter-acting a very loud environmental signal (as advocated from time to time)? Maybe in theory there would be perfect cancellation, but not in real practice.
BTW, one means of protection would be to set up a kind of two-eared Etymotic hearing-aid system whereby the only sound that gets to your ears is processed (limited, filtered, shaped, compressed, etc. which pricey medical hearing-aids do) by the hearing-aid system. Like a lot of acoustic materials, I bet ear plugs lose a lot of their moxie at very low Hzs and may not be good protection while in-the-ear phones might continue their blocking down low.... or maybe bone conduction negates any ear-canal effort at attenuation.
So, how do we assess the risk of damage from loud bass sound?
Thanks.
Ben
I have long wondered about damage to hearing from one-note reggae music, dance clubs, those aficionados in cars with booming sound systems, and, of course, my own systems too.
The usual hearing-damage standards (which are not based on compelling evidence) are stated as general SPL, and I believe dBA. Should a loud one-note bass be assessed for risk the same way? Does dBA go that low?
Odd, when your hearing deteriorates, the low frequencies are barely affected. Does that mean low frequency sound doesn't harm your hearing much?
Also, I have also wondered if your hearing really is protected by having a very loud "noise cancelling" signal counter-acting a very loud environmental signal (as advocated from time to time)? Maybe in theory there would be perfect cancellation, but not in real practice.
BTW, one means of protection would be to set up a kind of two-eared Etymotic hearing-aid system whereby the only sound that gets to your ears is processed (limited, filtered, shaped, compressed, etc. which pricey medical hearing-aids do) by the hearing-aid system. Like a lot of acoustic materials, I bet ear plugs lose a lot of their moxie at very low Hzs and may not be good protection while in-the-ear phones might continue their blocking down low.... or maybe bone conduction negates any ear-canal effort at attenuation.
So, how do we assess the risk of damage from loud bass sound?
Thanks.
Ben
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From what I have read both the OSHA and NIOSH permissible sound levels are in DBA, which rolls off below 1000 Hz, at 40 Hz down about 35 dB.
The OSHA 8 hour permissible level is 90 dBA slow, which would accept 125 dB SPL at 40 Hz.
Astronauts are exposed to in excess of 160 dB SPL LF on launch, they don’t seem to be deaf, neither do the old bomber crews that flew thousands of hours in airplanes that exposed them to very loud VLF.
The problem with loud LF is the top end is often turned up, if one mutes the subs, engineers will often find the top end of the system has suddenly got much “louder”.
The OSHA 8 hour permissible level is 90 dBA slow, which would accept 125 dB SPL at 40 Hz.
Astronauts are exposed to in excess of 160 dB SPL LF on launch, they don’t seem to be deaf, neither do the old bomber crews that flew thousands of hours in airplanes that exposed them to very loud VLF.
The problem with loud LF is the top end is often turned up, if one mutes the subs, engineers will often find the top end of the system has suddenly got much “louder”.
According to Profs Fastl and Zwicker, threshold of damage is around 110dB at 100Hz, and 130dB at 30Hz.
Not sure how that curve was determined.
What is worth mentioning is the fact that high frequencies are registered by the very first hearing cells in the cochlea, whereas low frequencies are registered by the last hearing cells. So bass sound waves have to travel past the HF hearing cells on their way in, which may go to explain why hearing loss always happens in HF first.
Not sure how that curve was determined.
What is worth mentioning is the fact that high frequencies are registered by the very first hearing cells in the cochlea, whereas low frequencies are registered by the last hearing cells. So bass sound waves have to travel past the HF hearing cells on their way in, which may go to explain why hearing loss always happens in HF first.
Noise induced hearing loss is primarily centered around 4000 Hz, where hearing is most sensitive, not HF.
The ear acts like a small horn, and the horn peaks in the 4000 Hz range.
HF hearing loss occurs with age and some ear diseases.
So 125 dB at 40 Hz is comparably as tolerable as 90 dBA broad music band?
Frankly, it would be odd to adopt a curve for perceptual sensitivity as applying to damage sensitivity. There's no necessary connection.
Yes, I don't think the OSHA standards have much solid basis. But good practical standards. I've been interested in motorcycle-caused hearing loss (for 51 years). No epidemiological evidence that I've ever seen.
Ben
Ben,
The quote you attributed to me in post #6 was by jwmbro. I replied to him in post #4.
If OSHA (or the more conservative NIOSH) had determined LF was a problem, they would specify unweighted or “C” scale rather than “A” scale, “A” scale rolls off the LF at the rate I noted in post #2, an example of the different weighting curves below.
As far as hearing loss on motorcycles, loud wind noise causes hearing loss over time. I recall a study of highway patrol officers back in the pre-internet era time when “air conditioning” meant opening up the windows. A high percentage of the patrolmen had hearing loss primarily in their left ears, which were exposed to more wind noise.
Short term tinnitus (ringing in the ears) results from exposure to loud sounds, if the ringing persists until exposure to loud sound again after a resting time period, hearing damage will result.
Having tested LF at levels of 120 + dB SPL at 40 Hz, I have experienced less tinnitus from that than from the same exposure time to a mid/ high noise like a saw or router at only 90 dBA.
Art
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This seems to be fairly accepted in academia, I have it from this textbook, Fastl and Zwicker are/were among the foremost experts on this subject, so I tend to trust their research results.
What Art says is of course equally correct, due to the human ear canal acting as a quarter-wave resonator, which offers gains of around 10dB centered around 4kHz, the frequencies from 2-5kHz are often among the first to go (I know this firsthand, as my right ear has over 10dB hearing loss right in that frequency range, despite the fact that it hears up to above 20kHz).
But at the same time, even higher frequencies are also among the first to go, I'm away with my laptop right now, but I'm fairly sure of this part, I'll double check my books tomorrow though to make sure.
What about compensation?
Do the logic in the brain analyze the frequency response and compensate for loss of frequencies? There are sounds I cannot hear, but when they are gone I "miss" them. Don't know if this makes any meaning. More often on hi-fi/RL, less so on headphones.
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What I am thinking is that the brain predicts there is information not detected because it influences the rest of the sound spectre, and compensates for it.
?
Do the logic in the brain analyze the frequency response and compensate for loss of frequencies? There are sounds I cannot hear, but when they are gone I "miss" them. Don't know if this makes any meaning. More often on hi-fi/RL, less so on headphones.
Edit:
What I am thinking is that the brain predicts there is information not detected because it influences the rest of the sound spectre, and compensates for it.
?
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This is how I feel about subsonics. We might not be able to hear 10 cycles as a sine wave, but when it's present with enough volume, it's going to affect other sounds.
OK, nice "out of box" thinking but not right. Audiological testing is done with pure tones (and other tests too, of course). But ordinary testing doesn't go below some medium low note, like 50 Hz.
Also, I can see the physiological connection between ear resonance and damage. But if true, then OSHA standards would have a curve with additional emphasis there (assuming their use of the dBA curve or any curve has any researched validity).
The presbycusis damage curve (and the generic industrial damage curve) show characteristic damage in upper frequencies and not lower. That curve isn't dBA-like.
BLATANT NATIONALISTIC NOTE WITH POLITICAL IMPLICATIONS (kidding of course): in Canada you can get seriously professional testing free under the government health program. Also, "free" tests at not always so professional dispensing hearing-aid places. No HiFi person should go without being tested - if only a "before" baseline.
Ben
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Please have a look at the other damage thread:
http://www.diyaudio.com/forums/lounge/48058-preventing-hearing-damage-loud-nightclubs-new-post.html
Ben
http://www.diyaudio.com/forums/lounge/48058-preventing-hearing-damage-loud-nightclubs-new-post.html
Ben
OSHA could have used "D" weighting, which is has about a 10 dB peak centered at 4000 Hz if they deemed it was needed.
They didn't, they used the more common "A" weighting, and worked out exposure based on that curve.
If one is exposed to a specific damaging HF frequency set, such as dentist's drills, the OSHA standards are too lenient, the NIOSH standards are more in line.
dBA Slow
NIOSH (1998)
85 for 8 hours
90 for 2.5 hours
95 for 47 minutes
100 for 15 minutes
dBA Slow
OSHA (1998)
90 for 8 hours
92 for 6 hours
95 for 4 hours
97 for 3 hours
100 for 2 hours
102 for 1.5 hours
105 for 1 hour
110 for 1/2 hour
115 for 1/4 hour
I'll have to get some more info on this and make a good statement to give to my "upstairs" people at work. The noise from the machines here at work is very loud, there is some ear protection about, but I really do not think it's enough. Most of the plugs are rated 23dB, but I managed to score a box full of 36dB orange ones, humongous difference ofcourse, but my ears fill up with grease and fibers after a while so I have to get them cleaned with some special stuff on a regular basis. Looking about for some bell ones or something similar, have no idea what to choose, or what to look at. How it fits and works is obviously important.
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If there's a good thing from noise, it's that I have become very good at discerning it, there is noise, and then there is noise, completely different!
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If there's a good thing from noise, it's that I have become very good at discerning it, there is noise, and then there is noise, completely different!
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I don't think I am being carelessly critical when I question if there really is solid evidence about what sound leads to what damage leading to what statandards. (Yes, there clearly are historic definitive cases of certain industrial settings and more broad and generic dBA levels leading to damage.)
So I am not convinced when I see OSHA or NIOSH or some Canadian standard quoted.
BTW, my favourite guru, Marshal Chasin says he thinks how you feel about the noise influences the level of damage. Also, in certain circumstances your ear can do pre-emptive protection on its own. Not to mention individual differences confusing everything.
Ben
So I am not convinced when I see OSHA or NIOSH or some Canadian standard quoted.
BTW, my favourite guru, Marshal Chasin says he thinks how you feel about the noise influences the level of damage. Also, in certain circumstances your ear can do pre-emptive protection on its own. Not to mention individual differences confusing everything.
Ben
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I far prefer deadphones to plugs. For several years I have been using GK Ultraphones, which use Peltor H10 Extreme Earmuffs with Sony 7506 headphone elements. They sound very good and they cut out 30 dB of mid/high noise, you can listen to music at a soft level while in an extremely noisy environment.
I recently bought the same earmuffs which are now marketed by 3M and more widely available at Home Depot and various other places. After using them in the shop, it was obvious that they were at least 10 dB (midrange noise sounds half as loud) more effective than the other 3 pairs of earmuffs of various makes I had been using.
The H10 are fairly heavy, but still are more comfortable than the other rather generic units.
The GK Ultraphones were the best investment in sound equipment I ever made, just wish I had gone to the H10 for shop use years ago, probably would have several dB less loss around 4K than I have now.
Art Welter
I recently bought the same earmuffs which are now marketed by 3M and more widely available at Home Depot and various other places. After using them in the shop, it was obvious that they were at least 10 dB (midrange noise sounds half as loud) more effective than the other 3 pairs of earmuffs of various makes I had been using.
The H10 are fairly heavy, but still are more comfortable than the other rather generic units.
The GK Ultraphones were the best investment in sound equipment I ever made, just wish I had gone to the H10 for shop use years ago, probably would have several dB less loss around 4K than I have now.
Art Welter
If you mean does the brain compensate for changes in frequency response due to physiological changes in your hearing, then the answer is yes it does, to a degree.
For example if you had a few dB loss of sensitivity near 4Khz your brain would get used to that spectral balance since the "error" in response would be present on everything you listened to. Eventually your brain "EQ's" its own perception.
Apart from gradual hearing loss with age examples of this adaption process are adapting to having long hair covering your ears vs fully exposed ears (hair over the ears reduces high frequencies but you don't really notice it) or adapting to having excessive ear wax build up.
It's amazing how much it can adapt before you start to notice there is something wrong. (By the time you notice a problem, it has reached its compensation limits...) As someone who used to have a lot of trouble with ear wax build up it was always a revelation when they were flushed out and everything sounded SO LOUD and crisp for the first few hours/days until the brain re-adapted to the new circumstances 😀
This same adaption mechanism is why we can't trust our ears to judge tonal balance without a reference - if you constantly listen to speakers with a particular tonal imbalance your brain will start to think the imbalance is a problem with your hearing and start to "correct" it somewhat. The tonally imbalanced speaker starts to sound more neutral. (Often mistaken for speaker break in... 😉 )
One thing to bear in mind though, is that while the brain can compensate quite a lot for frequency dependant hearing loss as far as perceiving tonal balance goes, it can do nothing to recover lost sensitivity.
So while 10dB hearing loss at 4Khz could potentially sound "normal" at higher SPL levels once the brain had adjusted its "perceptual EQ", at low SPL's there is still a loss of sensitivity - it would take 10dB more SPL before you could hear any sound at all, and the spectral balance would be off at low SPL's...
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Yes, I agree on this, music I can listen to for a long time at very high volume and seemingly no ill side effects, provided it's clean and little distortion. (my wife tells me she can hear my stereo playing very loud 2 blocks away, if it ain't concert level it ain't as much fun.) But when I come home from work I get the usual high freq tinnitus-like sound on both ears for some hours.
Very nice!
I did not know about those. Even though I am in strong opposition to Sony, it is very tempting to go for it. Music might make my day. 🙂
Yes, This is close to what I had in mind. But I was also thinking about frequencies you cannot hear, I think maybe the brain also use the rest of the body to sense sound, not only the ears. Sound travels through the body as you may know, Tap your knuckles and you can hear it through the bones of your body.
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I'm using a Peltor HTRXS7A for more then 15 years, still sounds the same after all this time.
I have had tinnitus for more then 15 years, I know why I'm wearing them.😉
Generally I put them on whenever I have to raise my voice to communicate or the noise irritates me.
That means most of the time...
I haven't had hearing loss in the last ten years and that's good proof that you should wear protection sooner then you're aware of.
Because when you think you need protection, it's already too late.
I have had tinnitus for more then 15 years, I know why I'm wearing them.😉
Generally I put them on whenever I have to raise my voice to communicate or the noise irritates me.
That means most of the time...
I haven't had hearing loss in the last ten years and that's good proof that you should wear protection sooner then you're aware of.
Because when you think you need protection, it's already too late.
An externally hosted image should be here but it was not working when we last tested it.
Yeeeeeaaahhh PELTOR ROCKS🙂
been wearing 98's for 10 years at work , i'd be deaf by now if I hadn't. Used to go to parties and dance right in front of the bass bins, not any worse for wear, bass was so intense my eyeballs shook ,or maybe it was my head as a whole🙂
been wearing 98's for 10 years at work , i'd be deaf by now if I hadn't. Used to go to parties and dance right in front of the bass bins, not any worse for wear, bass was so intense my eyeballs shook ,or maybe it was my head as a whole🙂
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