title: Killer whale (Orcinus orca) hearing: auditory brainstem response and behavioral audiograms.
abstract: Killer whale (Orcinus orca) audiograms were measured using behavioral responses and auditory evoked potentials (AEPs) from two trained adult females. The mean auditory brainstem response (ABR) audiogram to tones between 1 and 100 kHz was 12 dB (re 1 mu Pa) less sensitive than behavioral audiograms from the same individuals (+/- 8 dB). The ABR and behavioral audiogram curves had shapes that were generally consistent and had the best threshold agreement (5 dB) in the most sensitive range 18-42 kHz, and the least (22 dB) at higher frequencies 60-100 kHz. The most sensitive frequency in the mean Orcinus audiogram was 20 kHz (36 dB), a frequency lower than many other odontocetes, but one that matches peak spectral energy reported for wild killer whale echolocation clicks. A previously reported audiogram of a male Orcinus had greatest sensitivity in this range (15 kHz, approximately 35 dB). Both whales reliably responded to 100-kHz tones (95 dB), and one whale to a 120-kHz tone, a variation from an earlier reported high-frequency limit of 32 kHz for a male Orcinus. Despite smaller amplitude ABRs than smaller delphinids, the results demonstrated that ABR audiometry can provide a useful suprathreshold estimate of hearing range in toothed whales.
authors.affiliation: University of California Davis, Psychology Department 95616, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Szymanski
authors.forename: D E
authors.initials: DE
authors.lastname: Bain
authors.forename: K
authors.initials: K
authors.lastname: Kiehl
authors.forename: S
authors.initials: S
authors.lastname: Pennington
authors.forename: S
authors.initials: S
authors.lastname: Wong
authors.forename: K R
authors.initials: KR
authors.lastname: Henry
mesh_terms: D000818:Animals; D001299:Audiometry / Q000379:methods*; D001309:Auditory Threshold / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D004289:Dolphins / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006309:Hearing / Q000502:physiology*