Audiogram of a striped dolphin (Stenella coeruleoalba).
The underwater hearing sensitivity of a striped dolphin was measured in a pool using standard psycho-acoustic techniques. The go/no-go response paradigm and up-down staircase psychometric method were used. Auditory sensitivity was measured by using 12 narrow-band frequency-modulated signals having center frequencies between 0.5 and 160 kHz. The 50% detection threshold was determined for each frequency. The resulting audiogram for this animal was U-shaped, with hearing capabilities from 0.5 to 160 kHz (8 1/3 oct). Maximum sensitivity (42 dB re 1 microPa) occurred at 64 kHz. The range of most sensitive hearing (defined as the frequency range with sensitivities within 10 dB of maximum sensitivity) was from 29 to 123 kHz (approximately 2 oct). The animal's hearing became less sensitive below 32 kHz and above 120 kHz. Sensitivity decreased by about 8 dB per octave below 1 kHz and fell sharply at a rate of about 390 dB per octave above 140 kHz.
Kastelein
Ronald A
RA
Harderwijk Marine Mammal Park, Strandboulevard-oost 1, 3841 AB Harderwijk, The Netherlands. triessch@xs4all.nl
Hagedoorn
Monique
M
Au
Whitlow W L
WW
de Haan
Dick
D
D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D004289:Dolphins / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D010897:Pitch Discrimination / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography