Hello All,
I am interested in using AudioMoths in upcoming Participatory (Citizen) Science projects, but I am not an acoustical scientist and I am a little confused about how to use the AudioMoth's output in analysis. I have seen papers reference the output in dB Full Scale, dB-A (which I think is unlikely for default output), voltage, and a digital signal level. I want to understand exactly what the AudioMoth is outputting to the .WAV file when in default mode. 1. Can someone tell me precisely what the units are in the .WAV file that an AudioMoth in default mode produces? 2. Can someone point me to the reference that explains the output so that I can site it properly? I think I have read the AudioMoth papers, but I didn't quite find what I was looking for. Thanks in Advance! Trae
Hi, The normal output of the AudioMoth is a 16-bit WAV file that represents the digitised signal from the microphone. Each sample in the file is an integer between -32768 and +32767. The value represents the voltage at the input of the analog to digital converter on a scale from -1.25 to +1.25 volts. This can be related to the sound pressure by working backwards through the various amplifiers to the sensitivity of the microphone. It is possible to calculate a dB full-scale value from this but that's really just a logarithmic rescaling of the maximum value so doesn't really add any information. dBA is a measure of loudness scaled against human perception over a specific frequency range. In principle, an AudioMoth could be calibrated to produce this, but we haven't done so. What are you intending to use the AudioMoth for? It sounds like you are trying to measure an absolute sound level? Alex