Audiogram of the Virginia opossum(Didelphis virginiana)
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Data from:
Ravizza, R.J., Heffner, H.E., and Masterton, B.(1969) Hearing in primitive mammals: I, Opossum (Didelphis virginiana).Journal of Auditory Research, 9, 1-7. (Animals A & B)
Ravizza, R.J., and Masterton, B. (1972) Contribution of neocortex to sound localization in opossum (Didelphis virginiana). Journal of Neurophysiology, 35, 344-356. (Animals C, D, & E)
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Absolute thresholds (in dB re 20 µN/m2) for five opossums (designated A through E)
|
Frequency (in kHz) |
Individual Thresholds (in dB) |
Ìý Average |
||||
|
A |
B |
C |
D |
E |
||
|
.5 |
75 |
68 |
— |
83 |
65 |
73 |
|
1 |
58 |
64 |
— |
— |
— |
61 |
|
2 |
26 |
34 |
38 |
25 |
33 |
31 |
|
4 |
22 |
21 |
— |
— |
— |
22 |
|
8 |
29 |
28 |
27 |
18 |
25 |
25 |
|
16 |
21 |
17 |
— |
— |
— |
19 |
|
32 |
14 |
28 |
20 |
13 |
11 |
17 |
|
60 |
61 |
40 |
— |
— |
— |
50 |
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 |
0.6 |
— |
|
60 |
1.03 |
68* |
|
50 |
1.3 |
61 |
|
40 |
1.6 |
52 |
|
30 |
2.15 |
45 |
*Extrapolated value
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Additional Parameters:
Body weight =4 kg
Functional interaural distance= 273 µs
(Time required for sound to travel around the head from one auditory meatus to the other.)
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Comments: Threshold values taken from original data (Ravizza et al., 1969) and graphs (Ravizza and Masterton, 1972).