Fig. 9. Unequal contribution of right and left sides to bilaterally produced chaos. Chaotic sounds often contained harmonic windows, or brief moments of periodic oscillation, such as that seen around arrow b. Mockingbird `loud hew' calls (A) were always produced with flow through both sides of the syrinx for the entire duration of the call. In most cases (56 of 67 calls) one side alone appeared to contribute the majority of the aperiodicity in the call, while the contribution of the other side is more pure-tonal. (B) The difference in aperiodic behavior of the two sides is shown by examination of sound recorded inside the right and left bronchi and cranial thoracic air sac (obtained by high-pass filtering and amplifying thermistor and pressure transducer outputs). (C) 20 ms segment of the sound waveform, at the time indicated by arrow a in the spectrogram, illustrating the aperiodic nature of the oscillation. (D) Power spectrum of the sound taken at arrow a in the spectrogram (A). Additionally, the airflow in the right side (F_R) shows an aperiodic, rapid modulation, which are not present in the flow on the left (f_L). Other abbreviations as in Fig. 3.