Characteristics of ultrasonic vocalizations emitted by rats during shock-elicited aggression

Albino rats tested for shock-elicited aggression on occasion emitted periodic ultrasonic calls. The fundamental frequency of these calls was about 24 kHz, with harmonics appearing at 72 and 120 kHz, and the calls lasted as long as 3–4 sec. These calls were emitted by rats which had adopted an upright submissive posture following attack(s). These long 22–26-kHz calls may serve to inhibit or prevent unlearned behaviors in rats.