Remote masking in normal-hearing and noise-exposed chinchillas.
Remote masking (RM), the phenomenon whereby an intense high-frequency masking noise elevates thresholds for low-frequency signals, has been shown to be sensitive to various types of hearing loss in humans. We performed two experiments to evaluate the chinchilla as a model of RM and to examine changes in RM associated with temporary threshold shifts (TTSs) induced by low-frequency noise exposure. Thresholds for 0.5-, 1- and 2-kHz tones were measured in quiet, then in the presence of a narrow-band (300-Hz-wide) masking noise centered at 3 kHz. In Experiment I, effective masking was measured as a function of masker level, from 48 to 98 dB sound pressure level (SPL; referenced to 20 microPa), to determine threshold and rate of growth of RM in the chinchilla. In Experiment II, RM was measured before, during and after exposure to a low-frequency noise known to produce TTSs in chinchillas (i.e., a 0.5-kHz octave band noise at 90 dB SPL for 6 h/day for 10 days). The results show that normal-hearing chinchillas have the same pattern of RM as humans, and that a noise exposure that produces TTSs also produces rapid and significant changes in RM.
McFadden
S L
SL
Dept. of Communicative Disorders and Sciences, State University of New York at Buffalo 14214, USA. mcfadden@acsu.buffalo.edu
Henderson
D
D
Quaranta
A
A
D000818:Animals; D001309:Auditory Threshold; D002682:Chinchilla; D005072:Evoked Potentials, Auditory; D006309:Hearing / Q000502:physiology*; D006319:Hearing Loss, Sensorineural / Q000209:etiology; D006801:Humans; D009622:Noise / Q000009:adverse effects*; D010470:Perceptual Masking