The Acoustics Lab

Building a bioacoustics recorder capable of sound localisation

BACKGROUND

Acoustic detectors are widely used for the non-intrusive study of wildlife. It turns out that the data collected by these detectors have some similarities to radio astronomy data, which I’m much more familiar with. I’m interested to see how applicable some of the astronomical observation and analysis techniques are and if they can be used in bioacoustics. The Batto 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 and cross-correlation of their signals to measure directions and distances to sounds, from audible to ultrasonic.

A four-microphone array I built (The MarkII) provides provides fully-resolved directions. Find out more on this prototype project in the Batto Blog.

Current work

In June 2022 I began a project with Definium Technologies to design and build a pre-production circuit board assembly for a 8 microphone recorder. This includes designing, building, programming and testing the recorder hardware, firmware and low-level software. Definium has had significant previous experience in designing and building data loggers for research and industrial applications.  It is the only company in Tasmania with a complete end-to end electronics production system. This shortens the time scale of development, provides local employment, and connects research needs with instrumentation manufacture and commercialisation

 The recorder will have the capability of simultaneously recording signals from an array of 8 microphones at sample rates of up to 384 kHz. It will contain sensors for temperature, humidity, pressure and orientation, as well as GPS for location and time. It will be capable of wireless communications for configuration, control and data transfer. There will be sufficient on-board storage to support up to 2 weeks of recording at 10 hours per day. The main means of power supply is expected to be from internal rechargeable batteries but it will also be possible to attach external power including solar. The hardware will be enclosed in a weather-proof housing.

A final design for the board is nearing completion with the first production run a week or two following that.

I recently spoke about my acoustics work on the That’s What I Call Science podcast: Episode 195: From stars to bats & bird-song

Here is a video of a presentation I’ve gave recently on this work at the the Scintillometry Workshop 2022: "Fantastic Beasts and Where To Hear Them". 2022 Aug 29