Disturbing “tick” noises from the AudioMoth
Hello everyone,
I have a problem with my AudioMoth device and hope that someone may have had a similar experience or found a solution.
Almost every recording is preceded by a ‘ticking’ noise. Whenever there are no bat calls, the AudioMoth still produces short recordings by itself, and these contain a tick that seems to be generated by the device. I have attached an image of this noise.
My question:
Are there any known causes or settings that could cause these internal ticks?
And are there any ways to avoid these noises (e.g., via firmware or configuration)?
I appreciate any advice or experience you can share!
195 Views
Hi,
What you are seeing here is the data embedded into the WAV file that encodes the skipped sectors in the T.WAV file. These are blocks of 512 audio samples with values of -1, 0 and +1, but since the recording has no content, other than these values, your WAV viewer is scaling up the amplitude and showing them as audible sound. If you use the 'Expand AudioMoth T.WAV Files' option in the Config App, the file will get expanded to the correct 5 second length, the encoding block will get replaced by a period of zero value audio samples of the correct length, and the noise above will disappear. If the recording has some content, such as a bat pass, then this 'tick' also effectively disappears as your WAV viewer will not scale up the signal and it will be tiny compared to the actual sounds.
The full technical description of the T.WAV file format is here, but if you always expand the recordings then you will no longer see this additional embedded information.
https://github.com/OpenAcousticDevices/Application-Notes/blob/master/AudioMoth_Triggered_T_WAV_File_Format/AudioMoth_Triggered_T_WAV_File_Format.pdf
Alex