Figure 7.

Representative image of USV call runs and a pause. USV call series consisted of any group of calls with at least 4 calls spaced no more than 150 ms apart. Time between call series were considered pauses and may or may not have had isolated calls (groups of three or less calls) within the pause. The spectrogram X-axis represents time in seconds; the Y-axis is frequency in kilohertz (kHz). Relative intensity (“vocal loudness”) is measured in decibels (dB) and encoded by darkness of the signal; louder is darker. Some calls were not automatically detected by the software. These calls were labeled as “skipped” but were included in call series if they were visually and audibly confirmed by the reviewer. IVI = Intervocalization Interval. USV = ultrasonic vocalizations.