Variability in the temporal parameters in the song of the Bengalese finch (Lonchura striata var. domestica)

Abstract

Birdsong provides a unique model for studying the control mechanisms of complex sequential behaviors. The present study aimed to demonstrate that multiple factors affect temporal control in the song production. We analyzed the song of Bengalese finches in various time ranges to address factors that affected the duration of acoustic elements (notes) and silent intervals (gaps). The gaps showed more jitter across song renditions than did notes. Gaps had longer duration in branching points of song sequence than in stereotypic transitions, and the duration of a gap was correlated with the duration of the note that preceded the gap. When looking at the variation among song renditions, we found notable factors in three time ranges: within-day drift, within-bout changes, and local jitter. Note durations shortened over time from morning to evening. Within each song bout note durations lengthened as singing progressed, while gap durations lengthened only during the late part of song bout. Further analysis after removing these drift factors confirmed that the jitter remained in local song sequences. These results suggest distinct sources of temporal variability exist at multiple levels on the basis of this note-gap relationship, and that song comprised a mixture of these sources.

Statistical learning for vocal sequence acquisition in a songbird

“…This lack of an effect of sequence variability on the fidelity of sequence learning is consistent with a previous study in Bengalese finches that did not observe a relationship between the complexity of syllable sequencing and the acquisition of individual syllables 43 . In addition, because syllable sequencing has been shown to be linked to syllable timing 23,40,62,63 , we also examined whether variation in syllable timing could contribute to variation in the extent of sequence learning. However, the duration of the gap of a branch point transition (i.e., the silent interval between the branch point sequence and transition syllable) in the tutor's song did not predict whether the transition was dropped or retained by the pupil or the extent of similarity in transition probabilities between tutor and pupil's songs.…”

“…However, the duration of the gap of a branch point transition (i.e., the silent interval between the branch point sequence and transition syllable) in the tutor's song did not predict whether the transition was dropped or retained by the pupil or the extent of similarity in transition probabilities between tutor and pupil's songs. Given the natural correlations between syllable sequencing and timing in Bengalese finch song 40,62,63 , further experimental approaches are required to reveal the contribution of timing to sequence learning 64 .…”

Maturation‐dependent control of vocal temporal plasticity in a songbird

“…Sample sizes were slightly different among comparisons (young vs. early adult: n 5 12; young vs. late adult: n 5 9; early adult vs. late adult: n 5 11). To remove potential contamination by intrinsic slow fluctuations in singing tempo such as gradual slowing from morning to evening (Glaze and Troyer, 2006;Tachibana et al, 2015), we fit a smooth curve to the IOI data, and adjusted the original syllable, gap, and IOI data by subtracting the fitted curve. This curve fitting was performed as the least square fitting of a discrete cosine basis.…”

“…Songs consist of brief vocal elements (syllables) and intervening silent periods (gaps), with song-specific sequential patterns. Successive syllable pairs have specific gap durations which characterize the rhythmic pattern of the song (Glaze and Troyer, 2006;Matheson and Sakata, 2015;Sasahara et al, 2015;Tachibana et al, 2015). Juvenile birds copy not only acoustical morphology of syllables but also temporal structure of tutor songs, including gap durations (Williams and Staples, 1992;Takahasi et al, 2010).…”

“…Temporal variability (i.e., jittering in duration) among song renditions can be observed with greater variability in gaps than in syllables (Glaze and Troyer, 2006;Andalman et al, 2011;Tachibana et al, 2015), and this temporal variation is greater in earlier stage of song learning and gradually reduced over the song maturation (Glaze and Troyer, 2013). On the spectral features in syllables, the variability among renditions has been suggested to have some contribution to song learning (Tumer and Brainard, 2007;Sober and Brainard, 2012;Kelly and Sober, 2014;Woolley and Kao, 2015), for example, by expanding exploration range (Woolley and Kao, 2015).…”