Syllabic composition of the USVs of 129, B6, and F1 mice. (a) up: staccato (short repeats) (red) and chevron-wave (chevron repeats) (blue) of 129 (left), B6 (center), and F1 (right). The box represents short or chevron adjacently repeated regions. down: detailed view of the area in the triangle. (b) The ratio of each syllable type. 129 and B6 exhibited different use of short and chevron. F1 had a similar syllable composition to B6, but differed from 129. down: representative sonogram for each syllable produced by 129. * p < 0.01. (c) Sniffing and total number of syllables during sniffing. * p < 0.05.