Rs800cx monitor

For the playback experiments, the pigs were fitted with a heart rate measurement belt (Polar WearLink with W.I.N.D. sensor, wirelessly connected to an RS800CX monitor; Polar Electro Oy, Kempele, Finland) and earphones (Panasonic RP-HS46E-W Slim Clip on Earphones, Panasonic, Kadoma, Japan) that were fixed to the ears with self-adhesive bandages (Fixomull stretch, BSN medical GmbH, Hamburg, Germany). The earphones were connected to an MP3 player (San Disk 8GB Sansa Clip plus; Western Digital, San Jose, USA) in a small backpack on their back. The playback file and heart rate measurements were started simultaneously, and the beep of the heart rate monitor was later used to synchronize the playback file and heart rate measurements with the video recordings. In part A, the pigs heard 3 playback stimuli (1 IC, 1 RC and 1 CS in a pseudo-randomized and balanced order) in both ears during a session of 12 min (on day 15 post weaning). In part B, the session was repeated 3 times (on days 15, 17 and 19) to present the subjects with 3 playback stimuli (1 IC, 1 RC and 1 CS) × 3 playback modes (left ear, right ear, both ears) in a pseudo-randomized and balanced order.

The HRV was acquired using a H10 chest strap (Polar Inc., Kempele, Finland) and recorded using a RS800CX monitor (Polar Inc., Kempele, Finland). This wireless device was placed below the participant’s chest muscles, allowing a reliable recording [32 (link)].