Utterance and Breath Detection Using Acceleration Sensor in Underwater Breathing Equipment

We fabricated a cruciform PMMA beam (width: 2.5 mm, thickness: 0.5 mm) in a route (sectional size: about 19×7 mm) in which air passes in and out through in a snorkel. We then fixed a very small acceleration sensor (2×2×1 mm) onto the beam. By using the snorkel with the sensor in an experimental water tank, we were able to observe the frequency power spectra corresponding to the voice and motion of a subject. Our findings indicate that an acceleration sensor mounted on a breathing equipment can be used to monitor a diver's safety.