Audiogram of the horseshoe bat (Rhinolophus ferrumequinum)
Data from: Long, G.R., and Schnitzler, H.-U. (1975) Behavioral audiograms from the bat, Rhinolophus ferrumequinum. Journal of Comparative Physiology, 100, 211-219.
Absolute thresholds (in dB re 20 µN/m2) for three horseshoe bats
|
Frequency (in kHz) |
Average Threshold (in dB) |
|
|
2 |
92 |
|
|
5 |
54 |
|
|
10 |
27 |
|
|
15 |
-3 |
|
|
20 |
-3 |
|
|
25 |
1 |
|
|
30 |
2 |
|
|
35 |
8 |
|
|
40 |
24 |
|
|
45 |
20 |
|
|
50 |
12 |
|
|
55 |
-2 |
|
|
60 |
-4 |
|
|
65 |
7 |
|
|
70 |
31 |
|
|
75 |
10 |
|
|
80 |
-4 |
|
|
82 |
-1 |
|
|
84 |
1 |
|
|
86 |
3 |
|
|
88 |
8 |
|
|
90 |
10 |
|
|
92 |
13 |
|
|
94 |
19 |
|
|
96 |
26 |
|
|
98 |
40 |
|
|
100 |
53 |
|
|
110 |
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 |
3.35 |
108 |
|
60 |
4.3 |
103 |
|
50 |
4.8 |
100 |
|
40 |
7.1 |
98 |
|
30 |
9 |
97 |
Additional Parameters:
Body weight =22 g
Functional interaural distance= 55 µs
(Time required for sound to travel around the head from one auditory meatus to the other.)
Comments: Threshold values taken from graph in Long & Schnitzler, 1975, average of two bats with a third bat tested at high frequencies. Used change in heart rate or muscular activity in response to tones that signaled shock.