I use the AudioMoth with a external microphone underwater and to monitor marine mammal.
Question
1) Does the AM have a resonance, or excess gain at 20kHz? I tried a dozen indoor/outdoor settings, and there is always a band at 20kHz. The spectrum below is inside a quiet room. 2) In most of the indoor, quiet room, recordings, I see a rising thin line in the 30-50kHz range, see the above spectrum, the five panels cover about 20 minutes. Could this be a form of self-noise? 3) The clicking noise, I saw on other posts that this is SD card writing? I only see this occasionally. The image below was from inside a parked car at night - very quiet. Is the suggestion still to get the "Extreme" version of the SD card? Thanks - I love the unit. Keep up the good work - you are making a lot of research possible.
Brilliant. Can you post some details of the modification that you've made.
Is this a piezo-electric MEMS microphone directly in the water?
@Alex Rogers
Yes,this is a piezo-electric MEMS microphone directly in the water. and i will put the AudioMoth in a watertight enclosure, put the microphone directly in the water through cable penetrator for ROV.
I will post some details gradually。
That’s great. They were £25 each last time I checked but now seem to be down to £1. They are also supposed to be much more uniform in their response - less variability across manufacture.
What depth are you deploying it at?
About 2 meters!
Hello qdxiatao,
Can you share some more results?
Did you protect the piezo hole or it gets in direct contact with water?
How did it perform?
Thanks,
Tim
Did you put it in salt water? It is ok for the microphone?
Any Update?