Table 2.

$H_{RI\overline{x}}^2$ estimates for qualitative ultrasonic vocalization traits in the B6/D2 diallel cross.

Qualitative phenotypes	$H_{RI\overline{x}}^2$
Harmonics	0.57
Composite	0.68
Chevron	0.77
Frequency steps	0.77
Flat	0.78
Complex	0.84
Downward	0.87
Two syllable	0.88
Shorts	0.92
Upward	0.93

These phenotypes were only measured on postnatal day 8. Values for 700 calls from B6, 1,305 from D2, 2,047 from B6D2F1 calls, and 1,972 from D2B6F1. Calls were collected from 40 individuals, one male, one female, from five litters of each of the four genotypes.