The influence of military low-altitude flight noise on the inner ear of the guinea pig. Part I: Hearing threshold measurements.
The auditory thresholds of about 60 anaesthetized guinea pigs were determined at 3 or 4 frequencies between 2 and 20 kHz using the acoustically evoked brain stem potentials. The animals were then exposed to electro-acoustically reproduced MLAF noise with peak levels between 120 and 130 dB(A). The exposure occurred either once or else four times within either 3 or 60 minutes. The level of noise increased at 7.5 and 75 dB/s (slow and fast increase). TTS was then determined. PTS was measured one week later. In over half the animals, exposure to rapidly increasing noise level with a peak of 126 dB(A) induced PTS > or = 30 dB for at least one frequency. Exposure to a slowly increasing noise level with the same peak provoked significantly smaller PTS. 4 exposures to a rapidly rising noise level within 3 minutes induced significantly smaller PTS than the same dosage within 60 minutes. Only in the latter case was PTS greater than TTS.
Gehrig
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Meyer
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Ising
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Kuhl
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Schmidt
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Grützmacher
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D000337:Aerospace Medicine; D000401:Aircraft; D000531:Altitude; D000818:Animals; D001305:Auditory Fatigue / Q000502:physiology; D001309:Auditory Threshold / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D006168:Guinea Pigs; D009624:Noise, Transportation / Q000009:adverse effects*; D012307:Risk Factors; D013018:Sound Spectrography