There are acoustic glitches in my recordings, and I would like to know the cause of the sound anomaly and possible fixes.
This is what our spectrogram looks like:
And here are the example recordings from these two malfunctioning microphones: https://drive.google.com/drive/folders/1ZQINiZbWgIkgOtGfrsTq_WeOeHugRS_b?usp=sharing
it resembles and sounds like the noise we have from outdoors recordings when wind is present but we don't use a windscreen: the noise is concentrated in the lowest frequencies. Also, the noise can slowly or suddenly kick in, but its presence is totally unpredictable and sporadic (which complicates things).
We have a field team that is recording natural soundscapes in the tropics using SM2 Song Meters (Wildlife acoustics Inc.) and simple, self-built, open-design microphones after this article. The microphones essentially only consist of a MEMS microphone (Knowles, Invensense), have a SNR of 62-70 dB, a sensitivity of -36 dB, and we set the recorder amplification to 48 dB.
Unfortunately the field team has limited capacity for testing the microphones extensively and for sending me data remotely, so I am relying on the internet to investigate the issue. However, it was a bit more difficult than I thought, because people talk and mix up "hissing" noise (what is that?), "white" noise (this is clearly defined but not what we have here), or "static" noise (vaguely defined), and sample recordings are very rarely provided.