Print Email Facebook Twitter Receiving beam patterns in the horizontal plane of a harbor porpoise (Phocoena phocoena) Title Receiving beam patterns in the horizontal plane of a harbor porpoise (Phocoena phocoena) Author Kastelein, R.A. Janssen, M. Verboom, W.C. de Haan, D. TNO Defensie en Veiligheid Publication year 2005 Abstract Receiving beam patterns of a harbor porpoise were measured in the horizontal plane, using narrow-band frequency modulated signals with center frequencies of 16, 64, and 100 kHz. Total signal duration was 1000 ms, including a 200 ms rise time and 300 ms fall time. The harbor porpoise was trained to participate in a psychophysical test and stationed itself horizontally in a specific direction in the center of a 16-m-diameter circle consisting of 16 equally-spaced underwater transducers. The animal's head and the transducers were in the same horizontal plane, 1.5 m below the water surface. The go/no-go response paradigm was used; the animal left the listening station when it heard a sound signal. The method of constants was applied. For each transducer the 50% detection threshold amplitude was determined in 16 trials per amplitude, for each of the three frequencies. The beam patterns were not symmetrical with respect to the midline of the animal's body, but had a deflection of 3-7° to the right. The receiving beam pattern narrowed with increasing frequency. Assuming that the pattern is rotation-symmetrical according to an average of the horizontal beam pattern halves, the receiving directivity indices are 4.3 at 16 kHz, 6.0 at 64 kHz, and 11.7 dB at 100 kHz. The receiving directivity indices of the porpoise were lower than those measured for bottlenose dolphins. This means that harbor porpoises have wider receiving beam patterns than bottlenose dolphins for the same frequencies. Directivity of hearing improves the signal-to-noise ratio and thus is a tool for a better detection of certain signals in a given ambient noise condition. © 2005 Acoustical Society of America. Subject MarineUnderwater acousticsNatural frequenciesTransducersBeam patternsHorizontal planeSignal durationThreshold amplitudeAudio acousticsDirectional hearingMarine mammalsDolphinsEcholocationFrequency modulationHearing acuityPorpoiseSound detectionTransducerAcoustic stimulationEcholocationPhocoenaPitch Perception To reference this document use: http://resolver.tudelft.nl/uuid:8a8c23f8-1199-46cf-a848-af9b34d33eb2 DOI https://doi.org/10.1121/1.1945565 TNO identifier 238638 Source Journal of the Acoustical Society of America, 118 (2), 1172-1179 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.