Fig. 5.

Vocalizations become more call-like as more of the AFP is eliminated. A: the fraction of variance explained by each principal component. The 1st principal component (PC1) explains 34% of the variance. B: graphic representation of PC1 (normalized). Points indicate median, and error bars indicate 95% confidence interval for each feature from bootstrapping on birds. Features with values >0.354 (points above the dashed line) contributed the most to the acoustic variation along the axis. For PC1, these were SD of amplitude modulation (sAM), mean FM (mFM), SD of FM (sFM), and coefficient of variation of amplitude (CV amp), and they are positively correlated with each other along PC1. mAM, mean AM; mE, mean entropy; sE, SD of entropy; dur, duration. C: bootstrap estimation of the median location of the syllable projections for each group onto PC1. For each group, the median location of the projection is represented by a distribution that shows the best estimate (peak) and confidence interval (spread). Birds sustaining only HVC lesions (blue) produce syllables most similar to song syllables (black), whereas birds with both HVC and DLM lesions (red) produce syllables most like prelesion calls (dotted). Birds with both HVC and X lesions (green) produce syllables with characteristics falling between these 2 groups. The positive direction of the x-axis indicates high SD of AM and high mean and SD of FM.