Eigen values, percentage of total variation and vector loading values of the acoustic parameters for the first three principal components in the principal component analysis (PCA) for the principal carrier of simple 1-note calls (<i>N</i> = 540) (X̅ ± SE).

a 1st quartile frequency b 3rd quartile frequency c difference between the upper and lower frequency limits of the selection d inter-quartile range bandwidth e filtered root-mean-square amplitude. *F-test significant. Loading values of parameters that loaded strongly to one of the three principal components (values greater than 0.6 are bold typed). Eigen values, percentage of total variation and vector loading values of the acoustic parameters for the first three principal components in the principal component analysis (PCA) for the principal carrier of simple 1-note calls (N = 540) (X̅ ± SE).