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The application of the equal energy hypothesis (EEH) to interrupted, intermittent, and time-varying non-Gaussian noise exposures

2006; Acoustical Society of America; Volume: 120; Issue: 5_Supplement Linguagem: Inglês

10.1121/1.4787693

1520-9024

Roger P. Hamernik, Wei Qiu, Robert I. Davis,

Noise Effects and Management

Industrial data and animal research show that non-Gaussian (nonG) noise exposures are more hazardous to hearing than energy equivalent Gaussian (G) exposures. A statistical metric, kurtosis [b(t)], was shown to order the severity of noise-induced trauma following a nonG exposure relative to an energy and spectrally equivalent G exposure. Four groups of chinchillas were exposed to one of four different nonG interrupted, intermittent, and time-varying (IITV) noise paradigms over 19 days at an Leq=103 dB(A) SPL, with b(t)=25 or 50. Each daily exposure consisted of two 4.25-h periods with an hour break. Each 4.25-h exposure was interrupted for 15 min and each 5-day sequence was separated by a 2-day break. Each daily IITV exposure followed one of two different SPL temporal patterns that varied between 90 and 108 dB(A). All IITV exposures produced a toughening effect that did not alter the degree of noise-induced trauma. NonG noise produced as much trauma as a G exposure at 110 dB. Despite very different temporal paterrns for the b(t)=50 exposures, trauma was the same. Thus within a common class [i.e., the same Leq and b(t)] of nonG, IITV exposure, the EEH may apply. [Work supported by NIOSH.]