Real-time multiple machines sound listening using a phase-OTDR based distributed microphone

We propose and experimentally demonstrate a spatially tunable phase-OTDR based distributed microphone for listening to the sound of multiple machines. The distributed acoustic sensing capability, allied with the real-time spatial tuning, enables listening to a drill and to a cooling water system pump placed in two different sections along a single optical fiber, one at a time. The recorded acoustic waveform profile of both machines agreed with their operating cycles. Moreover, the sounds generated by both engines are successfully distinguished with the proposed method even when both machines are operating simultaneously.