Non-contact measurement of respiratory cycles using a microphone array

Previously proposed methods of respiration measurement have relied on thermistors or strain gauges, which must contact the body throughout the measurement, causing potential discomfort. Here, we develop a non-contact system that measures respiratory cycles by detecting the exhalation sounds using an array of microphones. Several respiratory-sound signals were recorded by the microphone array, and the respiratory signal was separated from the raw measurement data by the independent component analysis method. Respiratory analysis by the proposed method was compared with that of the previously validated thermistor method. Similar measurements were obtained by both methods, confirming that the proposed method eases the discomfort of users without compromising the measurement performance.