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 soundto 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.