Fig. 5.

Most degraded syllables returned to the structure of original syllables. By 8 weeks, syllable structure was more similar to pretreatment song than to song recorded earlier in recovery.A, Spectrographs of the first four iterations of the same syllable type taken from one randomly selected song bout in pretreatment records. The variability of several iterations of the same syllable type in normal song can be seen. B, Spectrographs of the first four iterations of the same syllable type from the same bird as in A taken from one randomly selected song bout recorded after 3 weeks of recovery.C, The first four iterations of the same syllable type from the same bird as in A and B taken from one randomly selected bout recorded after 8 weeks of recovery.A and C are more similar thanB is to either A or C. These syllables were taken from the song of a bird that did not learn new song elements. Notes are labeled with letters below each syllable.