Audiogram of the squirrel monkey (Saimiri sciureus)
Data from:
Beecher, M. (1974) Pure tone thresholds of the squirrel monkey (Saimiri sciureus). Journal of the Acoustical Society of America, 55, 196-198. average of two monkeys; free field
Green, S. (1975) Auditory sensitivity and equal loudness in the squirrel monkey (Saimiri sciureus). Journal of the Experimental Analysis of Behavior, 23, 255-264. average of three monkeys; headphones
Absolute thresholds (in dB re 2 µN/m2) for five squirrel monkeys
(designated A and B)
|
Frequency (in kHz) |
Average Thresholds (in dB) |
Average |
|
|
Beecher |
Green |
||
|
.125 |
46 |
64 |
55 |
|
.250 |
32 |
47 |
40 |
|
.500 |
19 |
31 |
25 |
|
1 |
9 |
17 |
13 |
|
2 |
7 |
17 |
12 |
|
4 |
15 |
17 |
16 |
|
8 |
1 |
8 |
4.5 |
|
10 |
-3 |
— |
— |
|
16 |
15 |
18 |
16.5 |
|
20 |
16 |
— |
— |
|
32 |
16 |
26 |
21 |
|
40 |
27 |
57 |
42 |
|
44 |
55 |
— |
|
|
46 |
70 |
76 |
73 |
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 |
— |
45 |
|
60 |
.100 |
43 |
|
50 |
.155 |
41.5 |
|
40 |
.250 |
39 |
|
30 |
.400 |
35 |
Additional Parameters:
Body weight = 900 g
Functional interaural distance = 302 µs
(Time required for sound to travel around the head from one auditory meatus to the other.)
Comments: Threshold values taken from graphs in Beecher, 1974, and Green, 1975.
Additional thresholds available in Fujita, S., and Elliot, D.N. (1965) Thresholds of audition for three species of monkeys. Journal of the Acoustical Society of America, 37, 139-144.
Note that the thresholds using headphone presentation are higher than those using free-field presentation, possibly owing to the difficulty of calibrating headphones especially at low frequencies. Because we used the average of the two audiograms in determining the lowest and highest audible frequencies, these may be conservative.