Mountable miniature microphones to identify and assign mouse ultrasonic vocalizations

Mouse ultrasonic vocalizations (USVs) are a promising model for studying vocal production. Although, in courtship interactions, males emit the majority of the USVs, female mice also produce USVs. In order to study the mechanisms of vocal production in freely behaving mice, it is necessary to identify the individual responsible for each syllable. Prior studies have used microphone arrays, but these are costly and require complex analyses to pinpoint the vocalizer. Here, we developed an inexpensive, ultrasound-sensitive wearable microphone to identify USVs from individual mice in socializing pairs. We reliably detected USVs and assigned 90% to a specific animal in a pair based on relative amplitude differences. When paired with video tracking, we increased the assigned percentage (97%) and described the courtship behavioral landscape in which USVs occur. These results offer a low-cost, simple method to study social communication between pairs of mice and other ultrasonically vocalizing animals.