Abstract
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.
Original language | English |
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Pages (from-to) | 420-425 |
Number of pages | 6 |
Journal | Aquatic Mammals |
Volume | 34 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2008 |
Keywords
- Anthropogenic noise
- Critical ratio
- Harbor porpoise
- Hearing
- Masking
- Odontocetes
- Phocoena phocoena