title: Noise-induced temporary threshold shift and recovery in Yangtze finless porpoises Neophocaena phocaenoides asiaeorientalis.
abstract: In Yangtze finless porpoises Neophocaena phocaenoides asiaeorientalis, the effects of fatiguing noise on hearing thresholds at frequencies of 32, 45, 64, and 128 kHz were investigated. The noise parameters were: 0.5-oct bandwidth, -1 to +0.5 oct relative to the test frequency, 150 dB re 1 μPa (140-160 dB re 1 μPa in one measurement series), with 1-30 min exposure time. Thresholds were evaluated using the evoked-potential technique allowing the tracing of threshold variations with a temporal resolution better than 1 min. The most effective fatiguing noise was centered at 0.5 octave below the test frequency. The temporary threshold shift (TTS) depended on the frequencies of the fatiguing noise and test signal: The lower the frequencies, the bigger the noise effect. The time-to-level trade of the noise effect was incomplete: the change of noise level by 20 dB resulted in a change of TTS level by nearly 20 dB, whereas the tenfold change of noise duration resulted in a TTS increase by 3.8-5.8 dB.
authors.affiliation: Institute of Ecology and Evolution, Russian Academy of Sciences. 33 Leninsky Prospect, 119071 Moscow, Russia.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Popov
authors.forename: Alexander Ya
authors.initials: AY
authors.lastname: Supin
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
authors.forename: Kexiong
authors.initials: K
authors.lastname: Wang
authors.forename: Lijun
authors.initials: L
authors.lastname: Dong
authors.forename: Shiyong
authors.initials: S
authors.lastname: Wang
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001299:Audiometry; D001305:Auditory Fatigue; D001309:Auditory Threshold; D005072:Evoked Potentials, Auditory; D005260:Female; D008297:Male; D009622:Noise / Q000009:adverse effects*; D019576:Porpoises / Q000502:physiology*; D020127:Recovery of Function; D013018:Sound Spectrography; D013997:Time Factors