title: A re-evaluation of auditory filter shape in delphinid odontocetes: evidence of constant-bandwidth filters.
abstract: The auditory filter shape of delphinid odontocetes was previously considered to be typically mammalian constant-quality in which filter bandwidths increase proportionally with frequency. Recent studies with porpoises demonstrate constant-bandwidth portions of the auditory filter. The critical ratios for a bottlenose dolphin were measured between 40 and 120  kHz by behaviorally determining the subject's ability to detect pure tones in the presence of white noise. Critical ratios as a function of frequency were constant, indicating the auditory filter acts as a constant-bandwidth system in this frequency range. Re-analysis of past studies supports these findings, and suggests the delphinid auditory system is best characterized as a constant-Q system below 40  kHz and a constant-bandwidth-like system between 40  kHz and 120  kHz before returning to a constant Q pattern at the highest frequencies.
authors.affiliation: Lockeed Martin, 3375 Koapaka Street, Suite I-500, Honolulu, Hawaii 96819, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Lemonds
authors.forename: L N
authors.initials: LN
authors.lastname: Kloepper
authors.forename: P E
authors.initials: PE
authors.lastname: Nachtigall
authors.forename: W W L
authors.initials: WW
authors.lastname: Au
authors.forename: S A
authors.initials: SA
authors.lastname: Vlachos
authors.forename: B K
authors.initials: BK
authors.lastname: Branstetter
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001301:Audiometry, Pure-Tone; D001307:Auditory Perception; D001309:Auditory Threshold; D001522:Behavior, Animal; D050681:Bottle-Nosed Dolphin / Q000523:psychology*; D005260:Female; D009622:Noise / Q000009:adverse effects; D010470:Perceptual Masking; D011571:Psychoacoustics; D017603:Signal Detection, Psychological