Change in echolocation signals with hearing loss in a false killer whale (Pseudorca crassidens)
Comparison of audiogram and masked hearing measurements indicate presbycusis with the subject. Masked hearing tests show the subject heard better at higher frequencies in 1988 than she did in 2004. Audiogram measurements are from Yuen et al. (2005) and masked hearing results are from Thomas et al. (1990).
Experimental setup. 1—experimental pen, 2—experimental shack, 3—stationing pad, 4—hoop, 5—response paddle, 6—target pen, 7—acoustic baffle, 8—visual screen, 9—monitoring camera, 10—target deployer, 11—recording hydrophone array.
Diagram of the sixteen-element hydrophone array. Each black circle represents the location of a single hydrophone.
Examples of the three click types produced by the subject. The representative waveform is shown on the left with the relative percentage of each signal type, and the representative normalized frequency spectrum is on the right.
Scatter plot of the center frequency versus peak-to-peak source level according to click type. The solid line represents the linear regression equation line of center frequency versus source level for all click types.
Change in signal characteristics for the average click for the subject between 1992 and 2008. to peak source level in dB re , frequency, frequency. 1992 data calculated from Au et al. (1995).
Average signal characteristics according to click type and relative frequency (%). to peak voltage, to peak source level in dB re , frequency, frequency.
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