is my listening volume normal? - Page 2

This is dangerous advice to be giving! In many countries prolonged exposure to 85dB in the workplace is illegal without hearing protection as this has been proven to be damaging. There is some evidence to suggest that prolonged exposure to even 75dB can contribute to hearing loss.

G

According to OSHA 90db is safe for 8 hours a day... So 80-85 will be fine for listening for a few hours a day.


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Where'd you get that number? I always read 85dB for 8 hours, with exposure time halving every 3dB. 90dB is only safe for about 2 hours.

 

And that's ignoring peaks, which can be much higher than mean volume level. I listen at a mean volume of around 70dB, and peaks can reach 80dB with some songs. Listening at 90dB would allow 100dB peaks, maybe more, and those peaks are only safe for 15 minutes total.

I read it right on OSHA's website. They say 8hrs max at 90db. http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9735


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Edited by jasonb - 9/26/11 at 5:47pm

Those numbers are using 5dB steps. I don't think that's the safest way to do it. A 3dB increase doubles power. Canada's safety requirements outline four different scenarios, two of which start at 85dB and two at 90dB, with 3dB or 5dB steps. Here's a quote:

 

"Most experts recognize the 3 dB rule as more logical. They argue that it is logical that if the sound level is doubled, then the allowable exposure time should be cut in half. It follows, then, that the allowable time should be halved for every 3 dB(A) increase in sound level. This is precisely the case if the 3 dB(A) exchange rate is used."

 

 90dB for 8 hours may be considered safe by U.S. safety regulations, but it is not necessarily safe.

Ok, well i did say that listening at 80-85 is fine for all day. Maybe 90 is high, but 80-85 should be fine for a lengthy listen.


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Yes, but that is just OSHA. In the UK and I believe the European Union too, the legal limit is 85dB rather than 90dB. The problem is that no one knows the real answer to what constitutes damaging levels. There are various reasons why:

1. Throughout our lives our hearing deteriorates, it's at it's best when we are babies and at it's worst in old age.
2. Everyone's hearing is slightly different and deteriorates at varying rates.
3. Except in extreme cases, it's very difficult to differentiate hearing loss caused by too much volume and natural hearing deterioration.

Various studies have shown that particularly in the developed world, hearing loss into middle and old age is getting worse, with more cases today of severe hearing loss than would be expected compared to studies of 40 years ago. The theory is that more noise in society is causing this problem, although there's little direct evidence for or against this theory. For the last 20 years or so science has been gradually reducing the recommended "safe" levels of sound but governments have been slow to enact these recommendations into law. My guess is that manufacturing and commercial lobbying interests use their influence to avoid the higher costs of lowering noise, providing hearing protection and testing that would be incurred with lower legal limits. It's also a concern that everyone uses the dB "A" weighted scale. This weighting was designed for use with low levels of sound and is inaccurate at higher sound pressure levels, usually indicating several dB less that than the real levels. The dB "C" scale should be used for levels above 60dB.

Two other points worth noting:

1. The ear has an autonomic defence mechanism to protect against high sound pressure levels called the Stapedius Effect. This mechanism seems to start kicking in at about 80dB and reaches maximum attenuation at about 110dB. Logic would suggest that if the human body considers it necessary to defend itself against levels of 80dB (and higher) that we should avoid too much exposure to this level of sound.

2. Strangely, the ear seems to react differently to the same sound pressure levels originating at different distances. So 85dB sounds quieter from speakers 20m away than it does from speakers which are only 3m away. Therefore, with sound mixing for cinema in a full cinema size room, the reference level is 85dB(C) but mixing in a small room (average sitting room size) the reference level is 79dB(C). This would suggest that using cans, the level should be even lower.

With all this in mind and to play it safe, I would recommend listening to cans at 75dBC or lower and speakers at 79dBC or lower. Maybe I'm a little paranoid as I rely on my hearing professionally but even so I could not, in good conscience, recommend levels much higher than this to anyone else.

G