[stereocilia]

Given the same decibel level, say....95 dB;

Which is more harmful for an extended period of time:
- 20Hz
- 200Hz
- 5,000Hz
- 15,000Hz

Just thinking out loud that it's not so much the level, but the content having something to do with it as well.

Bob

Great question, I wonder this myself.  I don't have a handy and certain answer, but my feeling is that the sensitivity of the ear sort of tracks with the sensitivity to damage from noise.  Most ears are most sensitive just above 3 KHz, and when permanent hearing loss appears due to overexposure, it is almost universally evident as a notch between 3 KHz and 6 KHz.  The greater the damage, the deeper the notch; and the "noise notch" appears in this frequency range if you are a musician or a machinist -- it doesn't matter.

I found something about exposure to low-frequency sounds.  You have to skip to section 7.  Notice that the effect in some studies is most evident at 2 KHz, far from the spectrum of the noise: http://www.defra.gov.uk/environment/noise/research/lowfrequency/pdf/lowfreqnoise.pdf
It seems that very few events are likely to contain enough very low (and for that matter, probably very high) frequency content in isolation to cause hearing damage.  So, in your example, I'm going to hang my hat on 5000 Hz, but I wouldn't be shocked to hear that somebody smarter than me says 15 KHz is the real answer.

[dyohn]

Exposure to any frequency band over 80dbSPL can damage your hearing, but since human ears are most sensitive in the 1 to 5Khz range, this area tends to be damaged first.  So, high SPL in this band would in theory be more damaging more quickly than SPL in other bands.,

[jimdgoulding]

High impact listening can be extremely fun and is my favorite mode of listening. It's thrilling to FEEL bass notes, have enough volume to hear background goings-ons, listen to a performance at a rational volume level to preserve what it's supposed to sound like. Volume is part of a system's tonality.  I typically don't go over 10 watts with 100db speakers, but the peaks are substantially higher than that. High impact isn't any good unless the sound is very,very clean, accurate AND engaging. BTW: High impact doesn't mean headache-level listening. The volume is up enough to fill a good size house to moderately high levels though.

What he said speaks for me, too.

[Bob in St. Louis]

I found something about exposure to low-frequency sounds.  You have to skip to section 7.  Notice that the effect in some studies is most evident at 2 KHz, far from the spectrum of the noise: http://www.defra.gov.uk/environment/noise/research/lowfrequency/pdf/lowfreqnoise.pdf

I scanned the first few pages and this looks like a VERY interesting read.
I think I'll stop scanning and read the entire paper.
The studies regarding American astronauts being exposed to 140+ dB with content ranging form 1Hz to 100Hz for extended periods of time definitely peaks my interest. aa

Thanks!
Bob