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. Author manuscript; available in PMC: 2011 Oct 5.
Published in final edited form as: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2010 Sep 18;197(1):45–59. doi: 10.1007/s00359-010-0585-6

Fig. 10.

Fig. 10

The pulse tone of this begging call is generated by the opening and closing of the labial valve in the right side of the syrinx. Labial adduction increases syringeal resistance causing the rate of syringeal airflow to decrease and the driving expiratory pressure to increase, so that air flow and pressure are 180° out of phase. The airflow trace does not reach zero due to the time constant of the thermistor. A biphasic sound pulse (arrow) occurs during each cycle. The period of the 370 Hz fundamental is equal to the interval between sound pulses. No correction has been made in the Wgure for the delay in the sound recording relative to that of airflow and pressure (see text). The interval between pulses appears to contain damped resonant oscillations. The absence of any oscillation in FLB indicates the left side of the syrinx is not producing sound. See Fig. 1 legend for abbreviations. (Magpie 1, 02–391)