Rats were purchased from Janvier Laboratories at 6 weeks of age. Upon arrival, rats were housed in pairs that were conserved throughout the experiment. After one week of acclimation, we identified each individual with a subcutaneous Radio Frequency Identification (RFID) tag (APT12 PIT tags; Biomark, Inc., Boise, The United States of America) inserted under gas anaesthesia (Isoflurane) with local analgesia (Lidor 20 mg/ml, with 40μl/10g). RFID tags were positioned in the lower part of the left flank. Rats were allowed to recover for at least ten days. We recorded dyadic interactions between two unfamiliar male rats of the same age (12–14 weeks of age). The focal animal encountered an unfamiliar animal of the same sex for one hour, in the LRT setup, with bedding. Light is diminished to 26 lux (within the cage). The two animals are left undisturbed for one hour. We coupled the Live Rat Tracker (LRT) system (https://micecraft. org/lmt; version 931) with the Avisoft Ultrasound Gate 416 (300kHz sampling rate, 16-bit format; trigger: level of this channel; pre-trigger: 1s; hold time: 1s; duration: >0.005s; trigger event: 2% energy in 25–125kHz with entropy <50%; Avisoft Bioacoustics, Glienecke, Germany) connected to a CM16/CMPA microphone (Avisoft Bioacoustics, Glienecke, Germany). LRT and Avisoft systems were synchronised.