4. Comparative Vocal Learning
157
A)
B)
control group
playback group
60
30
0
60
30
0
18
16
14
12
10
8
18 22 26 30 34 38 42 46
0
40 60 0
40 60
0
40 60 0
40 60
18 22 26 30 34 38 42 46
18
16
14
12
10
8
time [ms]
Time interval [ms]
Day 0
Day 20
Day 50
Day 100
frequency [kHz]
Fundamental
frequency [kHz]
Fundamental
frequency [kHz]
Figure 4.1. Lesser spear-nosed bat infant isolation calls. (A) Sonograms showing
changes during development for one infant. (B) Sinusoidal frequency-modulation
rate at day 50 for control and playback groups. Time interval between the first and
third frequency minima on the x-axis, fundamental frequency on the y-axis.
Values of maternal reference call are indicated with dotted lines. (From Esser 1994.
Reprinted with permission from Lippincott, Williams & Wilkins.)
157
A)
B)
control group
playback group
60
30
0
60
30
0
18
16
14
12
10
8
18 22 26 30 34 38 42 46
0
40 60 0
40 60
0
40 60 0
40 60
18 22 26 30 34 38 42 46
18
16
14
12
10
8
time [ms]
Time interval [ms]
Day 0
Day 20
Day 50
Day 100
frequency [kHz]
Fundamental
frequency [kHz]
Fundamental
frequency [kHz]
Figure 4.1. Lesser spear-nosed bat infant isolation calls. (A) Sonograms showing
changes during development for one infant. (B) Sinusoidal frequency-modulation
rate at day 50 for control and playback groups. Time interval between the first and
third frequency minima on the x-axis, fundamental frequency on the y-axis.
Values of maternal reference call are indicated with dotted lines. (From Esser 1994.
Reprinted with permission from Lippincott, Williams & Wilkins.)