title: Hearing threshold shifts and recovery after noise exposure in beluga whales, Delphinapterus leucas.
abstract: Temporary threshold shift (TTS) after loud noise exposure was investigated in a male and a female beluga whale (Delphinapterus leucas). The thresholds were evaluated using the evoked-potential technique, which allowed for threshold tracing with a resolution of ~1 min. The fatiguing noise had a 0.5 octave bandwidth, with center frequencies ranging from 11.2 to 90 kHz, a level of 165 dB re. 1 μPa and exposure durations from 1 to 30 min. The effects of the noise were tested at probe frequencies ranging from -0.5 to +1.5 octaves relative to the noise center frequency. The effect was estimated in terms of both immediate (1.5 min) post-exposure TTS and recovery duration. The highest TTS with the longest recovery duration was produced by noises of lower frequencies (11.2 and 22.5 kHz) and appeared at a test frequency of +0.5 octave. At higher noise frequencies (45 and 90 kHz), the TTS decreased. The TTS effect gradually increased with prolonged exposures ranging from 1 to 30 min. There was a considerable TTS difference between the two subjects.
authors.affiliation: Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow 119071, Russia.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Popov
authors.forename: Alexander Ya
authors.initials: AY
authors.lastname: Supin
authors.forename: Viatcheslav V
authors.initials: VV
authors.lastname: Rozhnov
authors.forename: Dmitry I
authors.initials: DI
authors.lastname: Nechaev
authors.forename: Evgenia V
authors.initials: EV
authors.lastname: Sysuyeva
authors.forename: Vladimir O
authors.initials: VO
authors.lastname: Klishin
authors.forename: Mikhail G
authors.initials: MG
authors.lastname: Pletenko
authors.forename: Mikhail B
authors.initials: MB
authors.lastname: Tarakanov
mesh_terms: D000818:Animals; D001299:Audiometry; D001309:Auditory Threshold / Q000502:physiology*; D050643:Beluga Whale / Q000502:physiology*; D004781:Environmental Exposure; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006309:Hearing / Q000502:physiology*; D008297:Male; D009622:Noise; D013018:Sound Spectrography; D013997:Time Factors