Male Mice Vocalize in the Ultrasound after Olfactory Exploration of Urinary Cues

<p>A cotton swab containing female mouse urine (top) was introduced at approximately 30 s into a 210-s trial. Arrow indicates the time of first contact with the cotton swab. Recorded acoustical power is represented as a function of time and frequency, with shading increasing with power. Power below 25 kHz was truncated. Bottom, an expansion of a 2-s period showing vocalizations in greater detail. Individual syllables, as identified by an automated algorithm, are spanned by magenta lines below.