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I have read that sound levels exceeding 70db spl can cause permanent ear damage given sufficient time.
Is this figure correct?
Because if so, then most of us are being exposed daily to levels in excess of this.
And I understand that not only is it the duration of exposure that determines the nature of the loss, but also that it is cumulative in the sense that repeated exposure also plays a part.
thanks
Kenji
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No, this figure is not correct. According to http://www.dangerousdecibels.org/hearingloss.cfm , 85dB is the critical level (corresponding to heavy traffic noise) which could lead to permanent hearing loss after 8 hours. Of course, these figures are somewhat arbitrary. In general just avoid any very loud and/or prolonged noise (use ear plugs if possible), especially if you are experiencing warning signs like tinnitus (even if only temporary). Our hearing system has simply not been designed by nature for the noise environments we are often exposed to today.
Thomas
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I found the figure of 70db on wikipedia.
But even in nature there are many sounds which could go above 85 right?
What about eating a carrot. This can be quite loud and more so because the crunching happens so near to the ear. How loud might this be?
Even shouting can be above that surely..
What about thunder?
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Another question is why do we have the ability to hear upto 20khz if anything above sat 10khz is of no importance?
Is it a protective mechanism since sensoryneural hearing loss tends to start higher up then work its way down?
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kenji schrieb:
I found the figure of 70db on wikipedia.
But even in nature there are many sounds which could go above 85 right?
What about eating a carrot. This can be quite loud and more so because the crunching happens so near to the ear. How loud might this be?
Even shouting can be above that surely..
What about thunder?
The 70dB figure would hold for a 24h exposure, which is a bit unrealistic. The 85dB figure holds for an 8h exposure (i.e. corresponding to a working day).
Impulse noise has to be very loud to cause any damage. Realistically, this could be only gunshots or fireworks going off right next to your head. So I wouldn't bother about the other options.
Thomas
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kenji schrieb:
Another question is why do we have the ability to hear upto 20khz if anything above sat 10khz is of no importance?
Is it a protective mechanism since sensoryneural hearing loss tends to start higher up then work its way down?
I do not really think that frequencies above 10 kHz could be vital for the survival of mankind, so I assume that this is a remnant from an earlier evolutionary state.
In any case, it doesn't lead anywhere to concentrate on such fine details of your hearing (or becoming even obsessed with them). I suspect it could on the contrary even produce and/or aggravate tinnitus. If there is nothing obviously wrong with your everyday hearing, I wouldn't thus bother about such fine details.
Thomas
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well one reason i bother with it is because i am an audiophile so it bothers me if at such a young age, my hearing has been affected and actually i still hear nearly upto 20khz therefore if (as in the email you sent me) these frequencies are cutoff it would affect my enjoyment of music. All these years i wondered why i could never achieve a perfect central sound image where you hear the singer coming from in between the speakers. Now I know why. There is about a 10db deviation between left and right ears at a given frequency, and this could be greater at others. I never imagined it was my ears.
Beitrag geändert von kenji (01-12-2007 20:37:24)
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This is what you told me in an earlier email if you dont mind me posting it.
'' Whether you are able to hear
higher frequencies all depends on how high your tinnitus extends. If you
can hear the test tone again at higher frequencies, then this means that
the frequency band of your tinnitus is rather narrow, if not, it means
that the tinnitus has a broader band. And the latter case would still in
all likelihood mean that it is just due to the tinnitus noise that your
can't hear the test tone. There is no way telling this with certainty
however, and neither is there a way to say that it is due to a damage of
your hearing rather than the tinnitus. You could only be sure if you
wait some time until the tinnitus gets weaker and then repeat the test.
But as I said already, the hearing above 10kHz is not really something
worth worrying about in my opinion.''
My question is: isnt otoacoustic emmission and auditory brain response a way of checking if it is the tinnitus which is affecting our ability to hear the test tone or hearing loss?
For people with chronic tinnitus if they do not have any other check than pure tone audiometry, they will be told that they have a hearing loss when it could well be the tinnitus affecting their hearing at that test frequency right?
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what about a typical day out in the shopping mall lasting a few hours?
that means if the trip were to last 3 hours, the max level allowed should be just over 88db, before damage.
Are shopping malls that quiet? I very much doubt it, and some of us work in these places so that's a full 8 hours and perhaps there's music playing in the shop and customers coming in and out, yet how come it is allowed to continue?
On the other hand it's hardly possible to operate a shop or supermarket below 88db that is fairly quiet.
so what does this all mean?
I've never really paid any thought to this as most people also wouldn't.
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I don't think that a shopping mall is that loud. Generally, unless you have to significantly raise your voice to make yourself understood to a person at a distance of about 1m, it shouldn't be a problem.
Thomas
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