AudioMoth

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AudioMoth is a low-cost ($49), full-spectrum acoustic logger, being developed by teams from Southampton and Oxford Universities. It can record at audible frequencies and well into ultrasonic frequencies. Hence it can be used as a static unattended detector for bats.

AudioMoth first came to our groups attention, when several group members took part in the BCT’s British Bat Survey South West pilot in 2019.

AudioMoth v1.1
AudioMoth v1.1

It is generally accepted that the AudioMoth is less sensitive, and produces noisier files that professional equipment. However group members were impressed with the survey results, easy of use, and most importantly low cost. Hence the committee have agreed to pioneer AudioMoth use on a landscape scale with our Mells Valley SAC Bat Landscape Survey.

Software

The Audiomoth team have produced a range of software specifically for use with AudioMoth:

  • Configuration App. – Every time the batteries are changed the Audiomoth has to be configured with this App to set it up for next use.
  • Flash App. – Enable quick automated updates to the software embedded on the Audiomoth to enable new features.
  • Time App. – Just sets the date and time of the device following battery change, now only used with custom firmware (such as the triggering branch).

Once the Audiomoth has been deployed and recordings made the mSD card will need to be removed and files transferred to a computer for analysis. Of the FREE software available we have found the following to be most useful.

  • Audacity – Excellent general purpose audio editing tool. Can be configured to show spectrograms by default.
  • Batclasify – A tool to help with the AutoID of bat species. Has many drawbacks (such as lumping all “big bats” together) over commercial products, but is FREE. Now a older program and not supported.

Other useful free programs:

  • Raven Lite – Can visualize sounds as spectrograms and waveforms.
  • Spek – Simple spectrogram viewer.

Audiomoth configuration

AudioMoth is a general purpose device that has been used in a wide variety of applications. Hence some degree of experimentation is needed to find the best settings that work for UK bats. The results of our testing of various configurations is summarised on this page.

Audiomoth Cases

AudioMoth is supplied as a tiny bare circuit board with integrated microphone and AA battery holder. Until recently some DIY skills and ingenuity were also needed to develop cases for the device. However in April 2020 a Official AudioMoth IPX7 Waterproof Case was made available.

Our thoughts on cases are linked to below:

Future reviews currently in progress: