Psychoacoustic Studies of Dolphin and Whale Hearing

SUMMARYLong-finned pilot whales are highly social odontocetes found in temperate and subpolar regions. This species is particularly known for its interaction with fisheries as well as its mass strandings. Recent tagging work has provided some information about pilot whales in the wild but, even though they have been successfully kept in captivity, little is known about their sensory capabilities. This study investigates the hearing abilities of a rehabilitated 2year old male long-finned pilot whale. A complete audiogram was collected using auditory evoked potential techniques that included measurements of nine frequencies from 4 to 100kHz presented as sinusoidally amplitude-modulated tones. The results indicated that the region of best hearing was between 11.2 and 50kHz and the subject had relatively poor high frequency hearing compared with other odontocete species. This study emphasizes the importance of collecting basic hearing measurements from new species, understanding diagnostic life histories as well as continuously increasing the sample size of audiometry measurements within and between odontocete species as animals become available.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Audiogram of a formerly stranded long-finned pilot whale (Globicephala melas) measured using auditory evoked potentials

Pacini

Nachtigall

Kloepper

et al. 2010

“…For many decades, the standard approach for examining hearing sensitivity in marine mammals has been behavioral testing (reviewed by Nachtigall et al, 2000). Behavioral audiograms have been determined for the bottlenose dolphin, Tursiops truncatus (Johnson, 1967), harbor porpoise, Phocoena phocoena (Anderson, 1970), common dolphin, Delphinus delphis (Belkovich and Solntseva, 1970), killer whale, Orcinus orca (Hall and Johnson, 1972), Amazon river dolphin, Inia geoffrensis (Jacobs and Hall, 1972), beluga whale, Delphinapterus leucas (Awbrey et al, 1988), false killer whale, Pseudorca crassidens , and tucuxi, Sotalia fluviatilis guianensis (Sauerland and Dehnhardt, 1998).…”

Section: Introductionmentioning

confidence: 99%

Live CT imaging of sound reception anatomy and hearing measurements in the pygmy killer whale, Feresa attenuata

Montie

Manire

Mann

2011

SUMMARYIn June 2008, two pygmy killer whales (Feresa attenuata) were stranded alive near Boca Grande, FL, USA, and were taken into rehabilitation. We used this opportunity to learn about the peripheral anatomy of the auditory system and hearing sensitivity of these rare toothed whales. Three-dimensional (3-D) reconstructions of head structures from X-ray computed tomography (CT) images revealed mandibles that were hollow, lacked a bony lamina medial to the pan bone and contained mandibular fat bodies that extended caudally and abutted the tympanoperiotic complex. Using auditory evoked potential (AEP) procedures, the modulation rate transfer function was determined. Maximum evoked potential responses occurred at modulation frequencies of 500 and 1000Hz. The AEP-derived audiograms were U-shaped. The lowest hearing thresholds occurred between 20 and 60kHz, with the best hearing sensitivity at 40kHz. The auditory brainstem response (ABR) was composed of seven waves and resembled the ABR of the bottlenose and common dolphins. By changing electrode locations, creating 3-D reconstructions of the brain from CT images and measuring the amplitude of the ABR waves, we provided evidence that the neuroanatomical sources of ABR waves I, IV and VI were the auditory nerve, inferior colliculus and the medial geniculate body, respectively. The combination of AEP testing and CT imaging provided a new synthesis of methods for studying the auditory system of cetaceans. Supplementary material available online at

“…Operant and classical conditioning techniques have been successfully applied to fishes, marine mammals and sea turtles to determine hearing capability ranges and maximal sensitivity ranges (e.g. lowest detectable level of a given stimulus or absolute threshold) (Patterson and Gulick, 1966;Popper, 1971;Coombs and Popper, 1982;McCormick and Popper, 1984;Yan and Popper, 1991;Kastak and Schusterman, 1998;Gerstein et al, 1999;Nachtigall et al, 2000;Houser and Finneran, 2006;Pacini et al, 2011;Gaspard et al, 2012;Martin et al, 2012). Many studies have involved the collection of both electrophysiological and operant conditioning data for hearing assessment, especially those that focus on marine fishes and mammal groups (Kastak and Schusterman, 1998;Sauerland and Dehnhardt, 1998;Szymanski et al, 1999;Casper et al, 2003;Wolski et al, 2003;Nachtigall et al, 2005;Yuen et al, 2005;Mulsow and Reichmuth, 2010;Reichmuth and Southall, 2011).…”

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confidence: 99%

Ontogenetic investigation of underwater hearing capabilities of loggerhead sea turtles (Caretta caretta) using a dual testing approach

Lavender

Bartol

2014

Sea turtles reside in different acoustic environments with each life history stage and may have different hearing capacity throughout ontogeny. For this study, two independent yet complementary techniques for hearing assessment, i.e. behavioral and electrophysiological audiometry, were employed to (1) measure hearing in post-hatchling and juvenile loggerhead sea turtles Caretta caretta (19-62 cm straight carapace length) to determine whether these migratory turtles exhibit an ontogenetic shift in underwater auditory detection and (2) evaluate whether hearing frequency range and threshold sensitivity are consistent in behavioral and electrophysiological tests. Behavioral trials first required training turtles to respond to known frequencies, a multi-stage, time-intensive process, and then recording their behavior when they were presented with sound stimuli from an underwater speaker using a two-response forced-choice paradigm. Electrophysiological experiments involved submerging restrained, fully conscious turtles just below the air-water interface and recording auditory evoked potentials (AEPs) when sound stimuli were presented using an underwater speaker. No significant differences in behavior-derived auditory thresholds or AEPderived auditory thresholds were detected between post-hatchling and juvenile sea turtles. While hearing frequency range (50-1000/1100 Hz) and highest sensitivity (100-400 Hz) were consistent in audiograms pooled by size class for both behavior and AEP experiments, both post-hatchlings and juveniles had significantly higher AEP-derived than behavior-derived auditory thresholds, indicating that behavioral assessment is a more sensitive testing approach. The results from this study suggest that post-hatchling and juvenile loggerhead sea turtles are low-frequency specialists, exhibiting little differences in threshold sensitivity and frequency bandwidth despite residence in acoustically distinct environments throughout ontogeny.