Electronic sound issue in Round 5 device

Has anyone else experienced bad audio on all recordings? I'm hearing a loud repetitive sound no matter the gain nor sample rate. It is a constant repetitive thud/static/propeller/synthesizer modulation sound. Audio is being recorded, but the electronic synth sound drowns out quite a bit of it.

I'm assuming either a bad part or a mistake in the soldering? Does anyone have suggestions on how to fix it?

I have included an audio sample below...

42 comments

42 Comments

Sofía Medellín

Sep 16, 2019

Thank you very much for this information, I will change the batteries before using them again this month. Is there anything I can do to avoid the noise due to the temperature?

Sofía Medellín

Sep 15, 2019

Sampling rate 384kHz, and the card is SanDisk Extreme 32GB (not extreme pro) the audio moth devices are in a forest (inside a ziplock), an yes, it ocurres in some recordings. Also, sometimes this noise appears too at 86kHz:

Alex Rogers

Sep 16, 2019

Replying to

The 86kHz band is the internal noise in the MEMS microphone. This is temperature sensitive and varies from microphone to microphone. Sometimes it's visible and sometime not. The other noise source is the SD card. It's not clear why some are more noisy than others but often it also seems to be when the battery voltage is low. Is that a possible explanation for the pattern that you see?

Alex Rogers

Sep 13, 2019

There is also some small background noise from the SD card writes but this seems to be more pronounced. What sampling rate are you using? Is this an Extreme or Extreme Pro SD card? Is the AudioMoth in a housing? Does is always occur or just on some recordings?

Sofía Medellín

Sep 12, 2019

Hi, I am having the same problem with the "clicking" noise at 18-20kHz. If I slow down the rate to 0.2 it sounds like a clock. I have 4 AudioMoth devices, all with Energizer AA batteries and sand disk extreme of 32gb. The noise appears in a few recordings regardless the device (it appears in all of them but we don't know what's activating it). However, when analyzing the spectrogram it becomes an issue because it overlaps with the sounds we are interested in.