Fig. 2

Representative spectrograms of ultrasonic vocalizations (USVs). USVs collected during a 5-min cage mate separation were analyzed. USVs were manually selected within spectrograms and categorized by call type. A Chirp calls were defined as low intensity USVs with a duration less than 0.02 s (20 ms). B Simple calls were defined as USVs longer than 0.02 s (20 ms) with “straight-line” intensity. C Harmonic calls were defined as a single USV with distinct tones of varying duration and intensity that create a “harmony”. Color-coded decibel level shown in key. kHz = kilohertz; s = seconds; dB = decibel