Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4356364 | Hearing Research | 2007 | 12 Pages |
Abstract
Kittens were exposed for 2Â h to a 1/3rd octave band of noise centered at 5Â kHz and at 120Â dB SPL. After the exposure, they were kept in a quiet room for at least 4 weeks, and until they were mature. The noise-exposed cats showed on average 16.5Â dB higher ABR thresholds and 13.2Â dB higher thresholds at the characteristic frequency (CF) than the control cats for frequencies between 4 and 16Â kHz. The frequency-tuning curve bandwidth at 20Â dB above threshold was significantly increased compared to controls in the CF region of the hearing loss. In noise-exposed cats, temporal modulation-transfer functions (tMTFs) to amplitude-modulated (AM) noise, but not to periodic click trains, showed a marked increase for modulation frequencies (MFs) below 6Â Hz. The vectorstrength in noise-exposed cats increased for all modulation frequencies below 32Â Hz for neurons with a CF in the range of the hearing loss. The tMTFs for AMnoise in the noise-exposed group were less band-pass compared to the controls, and in that sense the mild hearing loss could be considered as effectively reducing the central activation in the same way as a reduced sound pressure level. Effects of reduced central inhibition are visible in the broadening of frequency-tuning curves, and in the increased limiting rates for AMnoise.
Keywords
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Sensory Systems
Authors
Naotaka Aizawa, Jos J. Eggermont,