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. Author manuscript; available in PMC: 2012 Nov 2.
Published in final edited form as: J Neurosci. 2010 Oct 6;30(40):13246–13253. doi: 10.1523/JNEUROSCI.1130-10.2010

Figure 3. The only real period doubling found in the contact call of an adult male zebra finch.

Figure 3

A, Spectrogram of sound signal. Visual inspection shows new spectral components (arrowheads) starting at ~12 ms (dashed vertical line) at half the frequency spacing. B, The CR plot shows that the periodicity of the signal suddenly jumps from ~1 to ~2 ms, which is a strong indication for a period doubling. Upward arrows indicate the location of the extracted segments seg1 and seg2 for the topological analysis. ε = 0.001, which is 7.8% of the RMS value. C, E, Time series of the extracted segments: period-1 segment (seg1) (C) and period-2 segment (seg2) (E). The change in face color of the markers from white to black indicates time progression. D, F The corresponding orbits with time-delay τ = 0.09 ms. The linking number between period-1 and period-2 orbits is an odd integer LN = −7. This value is indicative of a real period doubling.