“Microphones exist in many shapes and sizes, and work in many different ways … These microphones all do the same thing: they convert sound waves into an electrical signal.
“It turns out, however, that with the addition of suitable software, microphones can detect more than mere audio signals. They can act as versatile sensors, capable of tuning into signals from inside the body, assessing the social environment and even tracking people’s posture and gestures. Researchers have reimagined microphones as multi-talented collectors of information. And because they are built into smartphones that can be taken anywhere, and can acquire new abilities simply by downloading an app, they are being put to a range of unusual and beneficial uses.”