Fig. 2
Examples of normalized amplitudes (uppermost panel) and spectrograms (middle panel) of stimulus sounds of the three cry types (natural cries, scrambled cries, and ultrasonic only cries) used in experiment 1 and experiment 2. The spectrograms within time-window (5.0–6.0 s) flanked by two black vertical lines are magnified and described in finer temporal resolution in the lowermost panels. The amplitudes were normalized by the maximum signal value of the natural cry waveform. Colour bars represent magnitude in dB