Audiogram of the manatee (Trichechus manatus)
Data from: Gerstein, E.R., Gerstein, L., Forsythe, S.E., and Blue, J.E. (1999) The underwater audiogram of the West Indian manatee (Trichechus manatus). Journal of the Acoustical Society of America, 105, 3575-3583.
Average absolute thresholds (in dB re 20 µN/m2) for two manatees.
|
Frequency (in kHz) |
Average Threshold (in dB) |
|
|
.015 |
49 |
|
|
.050 |
36 |
|
|
.100 |
33 |
|
|
.200 |
33 |
|
|
.400 |
41 |
|
|
.500 |
38 |
|
|
.750 |
20 |
|
|
1.5 |
10 |
|
|
3 |
6 |
|
|
6 |
-5 |
|
|
10 |
-6 |
|
|
12 |
-7 |
|
|
14 |
-12 |
|
|
16 |
-10 |
|
|
18 |
-4 |
|
|
25 |
4 |
|
|
28 |
16 |
|
|
32 |
26 |
|
|
45 |
39 |
|
Lowest and highest frequencies audible at sound
pressure levels (SPL) ranging from 30 to 70 dB SPL
|
SPL (in dB) |
Lowest audible frequency (in kHz) |
Highest audible frequency (in kHz) |
|
70 |
— |
— |
|
60 |
— |
— |
|
50 |
.014 |
— |
|
40 |
.410 |
45 |
|
30 |
.650 |
35.3 |
Additional Parameters:
Body weight = 350 kg
Functional interaural distance= not available
(Time required for sound to travel around the head from one auditory meatus to the other.)
Comments: Threshold values taken from table in Gerstein et al., 1999. Original sound level measurements were in dB re 1µPa and were converted to dB re 2 µN/m2 by subtracting 62 dB.