AudioMoth triggers too much

Hi Everyone,

Hope everyone is doing well. I've been using 4 AudioMoth with the exact same config for the past 2 months for ultrasonic night-recordings essentially, and everything's gone really well.

Unfortunately since 2 weeks approximately, one of them seems to be defective. Always using the same config for the 4 of them and using theme on the exact same place, i have one AudioMoth that is triggering way too much during the recordings sessions (a lot more than the other ones i mean).

There is no sleep or recording duration, and the trigger type is set to be a centered frequency of 40 kHz. The treshold setting is set to 1% for a minimum trigger duration of 1s.

Based on this setting, the AudioMoth are supposed to record only if an ultrasonic trigger is detected (i usually have one file each 20 minutes). But in the case of that AudioMoth, i have nearly 5 files per minute, and most of them are empty (i mean i only see noise pollution on it, indeed in the ultrasounds but it's not triggering my 3 other AudioMoth).

Does anyone have an idea of what i could do in order to fix that issue ? Maybe it's a problem with the microphone itself ?

Thanks in advance !

Just in case, i attach to this message the config i am using for my 4 AudioMoth.

Have a great day !