Table 1. Timeline of the experiment.

Day	Who	Event	Observation	Place	Sample size
					C	V1+	V2+
PND-30 to PND-5	Sows	Positive and negative handling treatments		Rearing pen	10	10	10
D0	Sows	Delivery		Rearing pen	9	10	9
D2	Piglets	Social Isolation Test 1 (SIT1) (5 min)	Simultaneous broadcast of V1 and V2 voices	Testing pen 1 × 2 m	35	36	39
D7	Piglets	Social Isolation Test 2 (SIT2) (10 min)	Piglet alone during two consecutive phases of 5 minutes each: Phase 1: No sound broadcast Phase 2: Sound broadcast (either V1 or V2)	Testing pen 2 × 2 m	34 (V1: 17, V2: 17)	36 (V1: 18, V2: 18)	37 (V1: 19, V2: 18)
D14	Piglets	Social Isolation Test 3 (SIT3) (5 min)	Simultaneous broadcast of V3 and V4 voices	Testing pen 1 × 2 m	20	20	20
D21	Piglets	Social Isolation Test 4 (SIT4) (5 min)	Piglet with a motionless human and broadcast of the voice associated prenatally with the maternal positive treatment (i.e. V1 for V1+ and V2 for V2+)	Testing pen 2 × 2 m	16	18	18