Noise Attenuating Properties of Earmuffs Worn by Miners. Volume 1: Comparison of Earmuff Attenuation as Measured by Psychophysical and Physical Methods.
NTIS: PB/83-257063 :46 pages
This contract was directed toward a study of the attenuating properties of earmuffs as worn by miners. Two attenuation measurement procedures were utilized. Human subjects were tested in a diffuse sound field according to threshold shift procedures recommended by the American National Standards Institute and a physical measurement procedure was accomplished in the same diffuse field on the same subjects with microphones placed simultaneously on the inside and outside of the muffs. All measurements were obtained on 1/3 octave of random noise. The results indicated that physical and psycho-physical attenuation measurements are in essential agreement at frequencies from 125 hz to 2 khz. Above 2 khz the psychophysical measurement demonstrates larger amounts of attenuation than the physical measurement. The difference in attenuation ranged from approximately 7.0 to 9.0 Db at frequencies of 4 khz and above. A possible explanation for the differences in attenuation is presented.
CP; Final Contract Report;
NTIS Accession No.
University of Pittsburgh