Signal conditioner

All recordings were performed in a sound-attenuated chamber (Industrial Acoustics, New York, USA) using an ultrasonic microphone (CM16/CMPA, Avisoft Bioacoustics, Berlin, Germany). During recording sessions, acoustic data were sampled at 250 kHz and digitized using an Avisoft signal conditioner and recorded with the Avisoft RECORDER software. Between sessions, the recording apparatus containing the mice was cleaned with 70% aqueous ethanol, rinsed with water, and dried.

Both male and female pups on postnatal day 8 (p8) were analyzed for their USV calls during a 5-minute separation from their mothers. Each pup was placed onto fluffy bottom bedding in a glass beaker and moved into a dark, soundproof box. The USV calls were recorded using an ultrasonic microphone connected to a pre-amplifier set at a 250 kHz sampling rate (UltraSoundGate 416H, Avisoft Bioacoustics). The acoustic data were digitalized by an Avisoft signal conditioner and recorded with Avisoft-Recorder software during the recording. The call number and types of the first 3 min of recording were analyzed manually according to the previous study [28 (link)].