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Energetic and informational masking of complex sounds by a bottlenose dolphin (Tursiops truncatus)

TitleEnergetic and informational masking of complex sounds by a bottlenose dolphin (Tursiops truncatus)
Publication TypeJournal Article
Year of Publication2016
AuthorsBranstetter B.K, Bakhtiari K., Black A., Trickey J.S, Finneran J.J, Aihara H.
JournalJournal of the Acoustical Society of America
Date Published2016/09
Type of ArticleArticle
ISBN Number0001-4966
Accession NumberWOS:000386932500050
Keywordsauditory masking; behavior; discrimination; maskers; noise; sea lions; sensitivity; signature whistles; spinner dolphins; stimuli

With few exceptions, laboratory studies of auditory masking in marine mammals have been limited to examining detection thresholds for simple tonal signals embedded in broadband noise. However, detection of a sound has little adaptive advantage without the knowledge of what produced the sound (recognition) and where the sound originated (localization). In the current study, a bottlenose dolphin's masked detection thresholds (energetic masking) and masked recognition thresholds (informational masking) were estimated for a variety of complex signals including dolphin vocalizations, frequency modulated signals, and a 10 kHz pure tone. Broadband noise types included recordings of natural sounds and computer generated sounds. Detection thresholds were estimated using a standard go, no-go adaptive staircase procedure. The same dolphin learned to associate whistle-like FM sounds with specific arbitrary objects using a three alternative, matching-to-sample (MTS) procedure. The dolphin's performance in the MTS task was then tested in the presence of the same masking noise types used in the detection task. Recognition thresholds were, on average, about 4 dB higher than detection thresholds for similar signal-noise conditions. The 4 dB difference is likely due to additional cognitive demands of recognition, including attention and pattern recognition. (C) 2016 Acoustical Society of America.

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