Passive acoustic detectors are widely used for the non-intrusive study of wildlife. The data collected have some similarities to radio astronomy data and so some of the analysis techniques may also be applicable. This blog describes my work to build a detector to collect and analyse audio data to try out some of these techniques as a proof-of-concept. I’m focusing on the use of multiple microphones (two initially) and cross-correlation of their signals to improve sensitivity and signal-to-noise as well as provide estimates of signal location and speed. Audio data at frequencies up 48 kHz are being recorded at present but the techniques will also work at higher frequencies..
The detector is based on a Raspberry Pi computer with a pair of digital microphones attached. The cost of components is relatively small, ~$100, making it a nice entry-level device for anyone who doesn’t mind wielding a soldering iron.
In the next post I’ll describe some work on using two microphones to improve sensitivity and show some initial results. Following that, I’ll look into methods to measure location and movement of signals.