Study of the effect of 350-Hz tone exposure on electrophysiological function of the inner ear of guinea pigs.
The effects of noise exposure were studied in fifty-nine 4- to 5-week-old albino Hartley guinea pigs with normal hearing (body weight 250-300 g). The following experiments and results were carried out: exposure to 350 Hz pure tones at 115 dB for 40 h and exposure to 350 Hz tones at 120 dB for 64 h. In order to investigate the effects of low-frequency tone exposures on the hearing of the guinea pigs, cochlear microphonics (CM), whole nerve action potentials (AP) and endocochlear potentials (EP) were measured. With a high-sound pressure, a decrease was observed in the CM maximum output voltage in the test frequencies of 2, 4 and 6 kHz while the CM threshold (pseudothreshold) of 6 kHz was elevated. Output voltage of the N1 potential of the AP using a 7-kHz tone burst decreased while the threshold of the N1 potential was elevated. An extension of latency and a decrease in the absolute value of the negative potential in EP were also observed.
Yamamura
K
K
Department of Hygiene, Asahikawa Medical College, Hokkaido, Japan.
Sugisawa
T
T
Inada
N
N
Matsui
T
T
Ishida
A
A
D000162:Acoustics; D000200:Action Potentials; D000818:Animals; D003051:Cochlea / Q000502:physiology*; D003055:Cochlear Microphonic Potentials; D003056:Cochlear Nerve / Q000502:physiology; D006168:Guinea Pigs; D006309:Hearing / Q000502:physiology*; D009622:Noise; D011930:Reaction Time