Fig. 8.
During calling, an unusual flow pattern occurred during short inter-call inspirations. (A) Helium inhaled during a short inspiration (labeled 1 on the left) is immediately exhaled at the end of the following call (expiration, labeled 2) This pattern was not present during a later helium pulse when calling stopped (right label 1). (B) During quiet breathing following the production of the call series the flow of helium also followed the typical pattern. (C) Expanded view of the unusual, rapid exhalation of helium during calling. The peak voltage output of the tracheal thermistor (FT) occurs at the end of the call, and this voltage is higher than during the initial inhalation, indicating a high concentration of helium in the excurrent air.