Ventilation, speech and singing must use facial musculature to complete these motor tasks and these tasks are fueled by the air we inhale. This motor process requires increase in the blood flow as the muscles contract and relax, therefore skin surface temperature changes are expected. Hence, we used thermography to image these effects. The system used was the thermography camera model FLIR X6580sc with a chilled detector (FLIR Systems Advanced Thermal Solutions, 27700 SW Parkway Ave Wilsonville, OR 97070, USA). To assure improved imaging, the room temperature was air-conditioned to +18° C. All images were recoded at the speed of 30 f/s. Acquired data were analyzed with FLIR Research IR Max Version 4 software and software filters.
In this preliminary study a male subject was imaged from frontal and lateral views simultaneously while he performed normal resting ventilation, speech and song. The lateral image was captured in a stainless steel mirror. Results showed different levels of heat flow in the facial musculature as a function of these three tasks. Also, we were able to capture the exalted air jet directionality. The breathing jet was discharged in horizontal direction, speaking voice jet was discharged downwards while singing jet went upward. We interpreted these jet directions as representing different gas content of air expired during these different tasks, with speech having less oxygen than singing. Further studies examining gas exchange during various forms of speech and song and emotional states are warranted.
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