Accession Number : AD0283403

Title :   EQUINOXIOUS CONTOURS FOR PURE TONES AND SOME DATA ON THE ' 'CRITICAL BAND' ' FOR TTS

Corporate Author : BOLT BERANEK AND NEWMAN INC CAMBRIDGE MASS

Personal Author(s) : CARTER,NORMAN ; KRYTER,KARL D.

Report Date : 01 AUG 1962

Pagination or Media Count : 1

Abstract : Experiment I tested the assumption that temporary threshold shift two minutes (TTS2) after exposure to intense sound is a constant function of level of the stimulus above its absolute threshold level. The assumption was confirmed for frequencies at and above 200 cps. At frequencies below 200 cps the level above threshold required for constant TTS2 is positively related to frequency. Experiment II showed that the over-all level of an octave band o noise must be about 5 db higher than that of a pure tone at the center frequency of the octave if TTS 2 from exposure to either the pure to e or octave band of noise is to be about the same, suggesting that the critical bandwidth for au itory fatigue is about one-third of an octave wide. The study also showed a marked difference in the lowest octave band (600-1200 cps) between the obtained TTS and that predicted from results by Ward, glorig and Sklar, (JASA, 31, 522-528). Experi ent III was condu ted with pure tone and onethird octave bands of noise. A constant width TTS critical band as a function of frequency agrees with more of the evidence obtained than the third octave band finding of Experiment II. (Author)

Descriptors :   *HEARING, *THRESHOLDS (PHYSIOLOGY)

Distribution Statement : APPROVED FOR PUBLIC RELEASE