Effect of two levels of masking noise on the hearing threshold of a harbor porpoise (phocoena phocoena) for a 4.0 kHz signal

• Published in: Aquatic Mammals
• Main Authors: Kastelein, Ronald A., Wensveen, Paul J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2008
• Subjects: Anthropogenic noise; Critical ratio; Harbor porpoise; Hearing; Masking; Odontocetes; Phocoena phocoena
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/effect-of-two-levels-of-masking-noise-on-the-hearing-threshold-of-a-harbor-porpoise-phocoena-phocoena-for-a-40-khz-signal(30faede0-789e-431a-9aab-17bda71539e1).html; https://doi.org/10.1578/AM.34.4.2008.420; http://www.scopus.com/inward/record.url?scp=70349140318&partnerID=8YFLogxK

The 50% detection hearing thresholds of a harbor porpoise for a 4.0 kHz narrow-band FM signal, presented at the background noise level in a pool and with two masking noise levels, were measured using a go/no-go response paradigm and an up-down staircase psychometric method. The masker consisted of a 1/6-octave noise band with a center frequency of 4.25 kHz. Its amplitude declined at 24 dB/octave on both sides of the spectral plateau. The absolute hearing threshold of the porpoise, found previously, was confirmed. The animal's auditory system responded in a linear fashion to the increase in masking noise. Since the narrow-band noise was off-center of the test frequency, the critical ratio of a harbor porpoise for 4.0 kHz tonal signals in white noise can at present only be estimated to be between 18 and 21 dB re: 1 μPa.