I'd like to share some experience in using cards larger than 32G. I record at 384kHz or 96kHz. I have 4 audiomoths, one has a 64G card, three have 128G cards. Furthermore I have a 200G card for long trips. It was 80% full after the last trip). All my cards are sandisk SDXC. I have nearly filled all 128G card, and over run one 128G card. After getting full it created names to the FAT table, but the file lengths were 0B, which was fine. One set of batteries lasted the whole 8 night recording. I have formatted the cards to FAT32 in linux (Ubuntu) using gparted - takes a few seconds. This may be possible also in the linux bash available in the latest Win 10 updates later than 1709. (I have not quite tried it yet.) There have been a couple of cases where some single recordings were missed when I had set 0 second interval, and recording of 300 or 600 seconds. Now I tend to set an interval of 2-5 seconds between the long recordings. These missed cases number less than 10 in over 1T data. One of my 119G recording failed, because I did not remember to reformat the card! That was a user's fault. No files written what so ever. It could be useful if audiomoth could warn about a wrongly formatted card during the setup. One thing to watch in any SD cards are the gold contacts. When you start to see dark lines in the contacts suggesting wear your card, a failure of your card may be immenent. I have had this happen on smaller cards (thrice in 16G/32G cards) in other devices. Audiomoth appears to handle the cards quite gently. I have been quite happy with large cards in the audiomoths.

Is there any update on the sound triggering. The ultrasound background can be very quiet except for a few intermittent bat calls. Is it possible to "monitor" and record only when the sound level in a tunable frequency or frequency range exceeds a specific intensity value. A prebuffer could be useful too in this case.