Re: TTS as surrogate for noise exposure measurement (Bastian Epp )

Subject: Re: TTS as surrogate for noise exposure measurement
From:    Bastian Epp  <bepp@xxxxxxxx>
Date:    Tue, 16 Apr 2013 09:49:01 +0200

Hi Bob, list! Just some thoughts from my side: - TTS has (if evoked by not-so dangerous exposure) a rather short time constant - I think for levels around 80 dB (don't nail me down on that) that is below (some) 10 minutes. Everything above (evoking longer lasting TTS) might be slightly longer. I recall that 2 (?) years ago there was a study by Chris Plack on Night club sounds (presented at BSA)...maybe there you find some more reliable data re the time constants ion connection with music. - Just measuring a pure-tone threshold might not be the best idea. Due to fine structure effects (e.g., work of Glenis Long et al.) you might misinterpret the result of there is a slight shift in FS due to whatever effect. FS is in general rather stable on the big picture, but for a pure tone I would not rely on the precision for a single point. If such an approach was taken, use either wobble-tones (with a frequency modulation, proposed by Zwicker) or narrowband noise. [I would rather suggest to get rid of in-ear headphones and to limit the level to a "comfortable" loudness (maybe evaluated with some weirdo Modern-Talking song to get rid of preference effects). The fear of damaging the innear ear without being a chicken should be the best protection...] Bests BAstian On 15/04/13 15:02, Bob Masta wrote: > I've been contacted by a young person in Hungary who is > concerened that his music listening habits may be damaging > his hearing. He saw that my Daqarta software has a built- > in SPL meter feature, and he wanted to know how to use it > to measure the headphone level of his music, so he could > keep it under 80 dB SPL. > > Unfortunately, he says he can't afford a calibrated > microphone, which would of course be needed for any SPL > measurements. > > Since this is just for "casual" purposes, not research, > etc, he'd probably be happy with some sort of rule-of-thumb > metric... but I don't know of any. I'm thinking here of > non-technical things like they recommend for aerobic > exercise, such as "walk fast enough so that you can just > barely carry on a conversation"... only for hearing. > (Anyone?) > > One problem is that I can't think of any household sounds > with a standard loudness. Another is that if he already > has some PTS he would get false assurance that his > listening levels were not too loud. > > So my question for the group is about using TTS. The > beauty of this is that it requires no absolute calibration. > He could measure his threshold at some specified frequency > in the morning before he starts his music listening, and > record the level in dB relative to full scale (whatever it > might actually be), then repeat it after listening and take > the difference. He can use Daqarta to do this for free. > > I think if he finds *any* shift it means his music is too > loud, but the converse is probably not true... especially > if there is already some PTS, which would presumably reduce > the amount of TTS. True? Any thoughts on this whole > approach? > > I have discarded one possible alternative approach, which > would be to listen at his usual level, then reduce the > level until he can just barely hear it and record how much > reduction that took. The problem with this dB-above- > threshold measurement is once again that if there is PTS > his higher threshold would make his music measure softer. > > Any other ideas? > > Thanks, and best regards, > > > > > Bob Masta > > D A Q A R T A > Data AcQuisition And Real-Time Analysis > > Scope, Spectrum, Spectrogram, Signal Generator > Science with your sound card! -- Bastian Epp Assistant Professor DTU Electrical Engineering ------------------------------------ Technical University of Denmark Department of Electrical Engineering ěrsteds Plads Building 352 2800 Kgs. Lyngby Direct +45 45253953 bepp@xxxxxxxx

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