So I put my new AudioMoth up a tree to monitor some bats for a few nights. I put it within the plastic bag provided. There has been quite a bit of water ingress (we've had some heavy rain). Curiously it seems to be working ok, and the sounds recording has worked fine. I'm guessing that if I put this within a rainforest for a month, it's quite likely to get trashed if housed within a plastic bag. Do you have any ideas as to what would help solve this? Thanks!
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Fantastic! Thank you Alex.
HI, The 15mm includes the depth of the batteries inside the holder. There are some more detailed photos on the GroupGets site here - https://groupgets.com/manufacturers/open-acoustic-devices/products/audiomoth.
Attempting to order waterproof junction boxes for these, but have a sizing question. Do the batteries increase the depth of the device substantially or are they seated inside the board (mostly included in the 15mm depth measurement)? If ever updating the page, it would be really helpful to see the back of the device on the specs page ("Audiomoth" tab). Thank you.
I did a lot of work on high frequency capacitance microphones back in the 70's. It is quite difficult to provide protection without affecting sensitivity and frequency response and that is basically just the price you have to pay. Especially at the higher frequencies where dimensions are becoming comparable with a wavelength (3mm at 100kHz ish). Membranes will reduce the sensitivity and reduce the top end frequency response - we had to use diaphragms of 3.5um Mylar to get over 1000kHz. Grids of any sort tend to do horrid things to the overall frequency response adding sharp peaks and troughs throughout the range. Probably not such a problem is you are just interested in identification unless you get a horseshoe bat just at an anti-resonant frequency, but you might get some funny effects in spectrograms and power spectra. Mainly it is important to be aware of the possible effects and take them into account when analysing recordings. For high frequency tropical species it might be best remove any protection unless it is explicitly required due to weather conditions. The MEMS microphone is quite well characterised in the Knowles Application Note on ultrasonic microphones, and there is another interesting technical document on the effect of different enclosures and ports on frequency response and sensitivity.
Hi Jez, These are the ones we've tried out. https://voir.en.alibaba.com/product/60595361396-801219240/Adhesive_vents_sticker_e_PTFE_acoustic_membrane_for_microphone_speaker_smart_watch_and_so_on_portable_products_.html?spm=a2700.8304367.prewdfa4cf.16.4d342e2cA11Vdx
Hi Andy, I was wondering if you have a link for the stickers you used over the holes drilled in your housings for the Belize project? Alasdair mentioned Goretex stickers when I met him but I've been unable to find anything online matching that description. If there's already something tried and tested I'd be keen to replicate it. Thanks.
I used an old margerine pot, wrapped in parcel tape! Worked fine, and there were