Hearing loss Temporary or more permanent?

Great advice Elizabeth. I too use a Shack digital meter and keep it handy for listening. For longer listening sessions, I adjust the volume so that the peaks (max setting, C weighted, fast response) hit just on 80. This way I know I am not doing any damage; I can relax and listen without worry. And I find that, after a few minutes, my ears take on increased sensitivity and "ramp up" their gain so that the preceived loudness increases with time.

Dbphd: Your comments make a lot of sense. Take a look at the excerpt I clipped from Wikipedia, which discussed the difference in using a 3db versus 5db exchange rate. The difference in listening threshold is quite significant.

For example, under the OSHA guidelines (which I believe are based on a 5db exchange rate), if the SPL is: (a) 90db, the recommended duration is 8 hours; and (b) 115 db, the recommended duration is 15 minutes or less. By contrast, as illustrated in the Wikipedia excerpt (presumably based on a 3db exchange rate), if the SPL is: (a) 90 db, the recommended duration is only 2 hours; and (b) 115db, 30 seconds!!!

So, last night I kept the SPL meter on while listening to various types of music. It required some discipline not to raise the gain, but I'm a believer now.

Bifwynne, I knew some of the people who were on the scientific committees that made the recommendations to OSHA.

Stevecham, I think you're doing the right thing by keeping peaks lower, but you need to know neither the auditory system nor other neural systems ramp up in sensitivity, although your perception may be concentrated with exposure. Adaptation is the mechanism, and thus it's easy to expose yourself to higher and higher levels.

Re fast v slow trajectory for an SL meter: Except for very high level peaks, gun shots usually, noise-induced hearing loss is a cumulative process. The military took advantage of what's called the stapedius reflex, in which the stapes is pulled slight away from the ear drum in response to a loud sound, by sounding a loud horn before firing a large gun. The purpose of such a reflex has been argued, but severe sounds are not part of our natural environment, so it's unlikely it was developed over time to provide protection from such sounds. Using fast trajectory is OK, but it makes it more difficult to estimate the cumulative SPL exposure.

Dbphd: Seems like you have a better grasp on this issue than most.

FYI: I set my Radio Shack meter at the C weighted/fast response levels, just like Stevecham. If I used the controls properly, I tried to hold the volume down to about 80-85 db continuously, with an average SPL of roughly, say 80db. However, for certain types of music, say classical, the SPL jumps all over the place, even though the "avergae" SPL might be in the low to mid 80s.

So my question is this: can you provide some safe guidelines when setting system volume, especially for classical music?? Thanks -- for all of us.

Bifwynne, as a general rule if it feels comfortable to you it's probably OK. If you think you're pushing it, turn the level down a bit. You might start by finding a level where soft jazz (e.g. Bill Evans), Bach, and Mozart feel right, then look at your attenuator to find a reference level. Peaks from that reference in more bombastic music (e.g. Mahler or Stravinsky) are unlikely to do any damage to your hearing. The OSHA guidelines are aimed more at the kind of continuous noise exposure found in a workplace. Bottom line: Use common sense; if it seems loud, it probably is.

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