title: Energetic and informational masking of complex sounds by a bottlenose dolphin (Tursiops truncatus).
abstract: 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.
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, Number 200, San Diego, California 92106, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Branstetter
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, Number 200, San Diego, California 92106, USA.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Bakhtiari
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, Number 200, San Diego, California 92106, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Black
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, Number 200, San Diego, California 92106, USA.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Trickey
authors.affiliation: United States Navy Marine Mammal Program, Space and Naval Warfare Systems Center Pacific, Code 71510, 53560 Hull Street, San Diego, California 92152, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Finneran
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, Number 200, San Diego, California 92106, USA.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Aihara
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold; D050681:Bottle-Nosed Dolphin; D009622:Noise; D010470:Perceptual Masking