Abstract: A method for rapidly and accurately measuring the acoustical attenuation effectiveness of various personal hearing protection devices as worn, particularly in-the-ear type protectors under conditions of normal fit in a working environment having significant ambient noise. The method comprises presenting an audio signal to an ear both with and without the hearing protector in place and noting the difference in intensity of the applied signal, measured in decibels, required to obtain the same perceived amplitude level in each case. The perceived amplitude level may be either the threshold of the subject's hearing perception or a supra-threshold reference point determined by a comparison of the test ear signal with a reference signal in the contralateral ear to allow for testing in ambient noise levels of high or fluctuating intensity. The test signal is preferably a multi-frequency complex signal having a preweighted power spectrum which emphasizes those frequencies which are particularly hazardous.

Abstract: A portable device primarily for use in determining the effectiveness of various personal hearing protectors in attenuating hazardous noise. The device comprises an electronic circuit for generating audio test signals at varying amplitude levels, and a display for providing numerical indications usable to measure accurately the difference in amplitudes between the respective audio signals. The test signal increases or decreases in loudness in response to a subject-operated hand switch which also triggers display of the appropriate numerical indication at amplitude levels determined subjectively by the individual being tested. The electronic circuit of the device preferably is capable of producing such test signals in complex, multifrequency form with preweighting of the power spectrum of the signal so as to emphasize the most potentially hazardous frequencies.