The required subtractive or additive compensatory values at each sampled frequency are readily available for the Rat Shack meter, a calibrated unit isn't absolutely required---just a little math. A search over on AudioAsylum netted results for me quickly. As to the prolonged exposure at 85 db. question, I suspect industrial safety specs err on the side of too much noise exposure. Quite some time ago, one of Stereophile's writers referred to a study done in the Andes of elderly men who had had no exposure to the ambient noise levels that pervade our modern world. The researchers were quite surprised to find that the study subjects had hearing acuity as good as teenage boys in our society! Now I suppose that single study wouldn't allow one to make the direct conclusion that noise exposure levels cause hearing damage at far lower levels than we suppose, but it gives great pause for thought I think.
Reasonably accurate, inexpensive dB meter--ideas?
This would not be to tweek the system, just to monitor my listening levels to avoid potentially unsafe volume exposure {but still make sure it's as loud as I can get away with :)}. Are there any recommendations for a reasonably accurate, inexpensive (under ~100 bucks or so) dB/SPL meter?