Toothed whales (Odontoceti) use biosonar for orientation and echolocation of prey by emission of short sound pulses, and subsequent reception and processing of returning echoes. The last 30 years of research have provided a wealth of information about the production, transmission and reception of so...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.664.3072 http://marinebioacoustics.com/files/2004/Madsen_et_al_2004b.pdf |
| Summary: | Toothed whales (Odontoceti) use biosonar for orientation and echolocation of prey by emission of short sound pulses, and subsequent reception and processing of returning echoes. The last 30 years of research have provided a wealth of information about the production, transmission and reception of sound in dolphin sonar systems along with insights in their detection and discrimination capabilities (for a review, see Au, 1993). These studies have not only demonstrated that the production and transmission of toothed whale sonar clicks show considerable interspecific variation, but also that conspecifics may produce very different signals, depending on the detection task and the acoustic umwelt (Au, 1993). The latter is exemplified by the fact that signals from echolocating bottlenose dolphins Tursiops truncatus increased by 40·dB in source level (SL) and one octave in frequency emphasis when their signals were measured in open pens (Au et al., 1974) as compared to measurements of animals in concrete tanks (Evans, 1973). Target detection experiments in pens have subsequently provided a multitude of physiological data about the maximum sonar system capabilities of a limited number of delphinid species so that comparison with bats (Au, 1997) and ideal receivers (Au and Pawloski, 1989) can be made. While such controlled experiments with trained animals are vital for understanding the basic properties and performance of odontocete sonar systems, they may not provide data that fully reflect the properties and use of biosonar signals in natural habitats with conspecifics, predators and prey (Au, 1993). This reservation has been confirmed in a terrestrial echolocator, the big brown bat Eptesicus fuscus. Sonar signals recorded in the field were significantly longer, with longer interpulse intervals and greater variability in bandwidth than signals recorded in the laboratory (Surlykke and Moss, 2000). Therefore, data from controlled experiments with trained animals should be |
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