Fig. 1.

Typical zebra finch song structure, as revealed by sound-spectrographic analysis. Top, The motif is usually preceded by an introductory note (labeled i) repeated a variable number of times. The motif itself consists of a series of discrete sounds, usually delivered in the same order, that we call syllables and that are numbered here 1–9. Syllables have a distinct acoustic structure, with a beginning and end marked by a silent interval, as in syllables 1 and2, or by an abrupt change in frequency modulation, as insyllables 7–9. Clusters of syllables (e.g.,syllables3–6 and 7–9) separated from previous and subsequent sounds by a longer silent interval (>10 msec) are called chunks. The motif is usually repeated a number of times, forming a bout (see Fig. 9). Bottom, Repetitions of the motif, shown here at the beginning of three successive song bouts, are presented. Notice that with the exception of the variability in the number of introductory notes, the fine structure of the motif is highly stereotyped.