Are American National Standards Institute sound level meter tolerance limits adequate for sound dosimeters?

Abstract

Sound dosimeters afford many advantages over sound level meters for measuring sound exposure levels, and will likely assume a prominent place in hearing conservation programs in the future. This paper discusses the appropriateness of the ANSI Types 1 and 2 sound level meter specifications proposed for dosimeters. For any given set of ANSI sound level meter tolerance limits in decibels at a specified frequency, the dosimeter must have its readout tolerances expressed in percentage units for each level and time of exposure. Therefore, calculations have been made for exposure levels ranging from 85 to 115 dB(A) in 5 dB steps for exposure times of 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 h at 34 preferred frequencies from 10 to 20 000 Hz. Corresponding dosimeter readout tolerance limits have been calculated for both ANSI Types 1 and 2 specifications based upon the present OSHA formula. Wide tolerance limits result from these calculations at high frequencies, high levels, and long exposure times. For example, the +6.5 and −5.5 dB Type 2 sound level meter tolerances at 6300 Hz, correspond to a dosimeter reading tolerance of +144 to −53 for a 100% exposure. Alternate tolerance limits are discussed.