Figure 3. Differential re-development of song features.

(A) Mean correlation plot for all animals illustrating the development of the frequency modulation (FM) distribution in the song during the development (T₁+) and re-development (T₂+) of song. The correlation plot illustrates a gradual FM development during T₁+, followed by a short phase of FM re-development during T₂+. (B) Group statistics demonstrating that the stabilization of the FM distribution in the song took less time during a 2^nd testosterone treatment (red bars) than during the 1^st treatment (blue bars). (C) The peak day-to-day increase in the FM CC (d_max) was significantly higher during a 2^nd testosterone treatment than during the 1^st treatment. (D) Mean correlation plot for the syllable bandwidth showing a gradual development during a 1^st testosterone treatment (T₁+), followed by an immediate recovery of syllable bandwidth during a 2^nd treatment (T₂+). (E) Group statistics demonstrating that stable syllable bandwidths were achieved more quickly during a 2^nd testosterone treatment (red bars) than during the 1^st treatment (blue bars). (F) The peak day-to-day increase in the syllable bandwidth CC (d_max) for T₁+. D_max could not be calculated for T₂+, as we observed no developmental increase of this song feature during the 2^nd testosterone treatment. (G) Deterioration in the distribution patterns of all analyzed song features during absence of song production (T₁-), and (H) subsequent recovery of song features during testosterone-induced re-development of song (T₂+). Grey bars in A and D indicate the SEM. Columns in B,C and E-H represent the mean ± SEM and open circles indicate individual data points (*p<0.05, **p<0.01, ***p≤0.001, paired t-test (B,C,E,F) and one-sample t-test (G,H), n = 6 animals). Source data for acoustic features are available in the Figure 3—source data 1.

Figure 3—figure supplement 1. Differential re-development of spectral song features.

(A) Mean amplitude modulation (AM) correlation plot for all animals. The AM distribution demonstrated a gradual consolidation during the 1^st testosterone treatment (T₁+), and displayed a short phase of re-development during a 2^nd testosterone treatment (T₂+) (B,C). Both mean frequency (D–F) and wiener entropy (G–I) demonstrated a gradual development during the 1^st testosterone treatment (T₁+) followed by an immediate recovery during a 2^nd treatment (T₂+). D_max could not be calculated for T₂+ in F,I, as we observed no developmental increase of these song features during the 2^nd testosterone treatment. Grey bars in A, D and G indicate the SEM. Columns in B,C, E,F, and H,I represent the mean ± SEM and open circles indicate individual data points (**p<0.01, ***p≤0.001, paired t-test, n = 6 animal).

Figure 3—figure supplement 2. Development and re-development of spectral song features.

Example song feature histograms illustrating the gradual acquisition during a 1^st testosterone treatment (T₁+) and the rapid recurrence during a 2^nd treatment (T₂+) for (A) frequency modulation, (B) amplitude modulation, (C) bandwidth, (D) mean frequency, and (E) Wiener entropy. (F,G) Example spectral derivative spectrograms from stable songs at 200 days after a 1^st testosterone treatment (T₁+ 200), plastic songs at 3 days after a 2^nd testosterone treatment (T₂+ 3), and stable songs 30 days after a 2^nd treatment (T₂+ 30).