Has config v1.12.1 configured correctly

I've regularly run bat monitoring for 5 or more nights on 12 Audiomoths. In the past the AudioMoth-config app was v1.9.1, but for the latest session in April 2025 it was updated to v1.12.1 due to a prompt. The AudioMoths were not flashed this time due to time pressure, but they were flashed in February 2025 and used in another application with AudioMoth-config v1.9.1 and appeared to work normally.

The data collected during the April 2025 session was about 15GB over 12 devices, compared with usually much more than 100GB previously.

I've compared the CONFIG.TXT files from the April 2025 and April 2024 sessions and don't see any changes to my settings, see two examples below. Weather and environmental conditions were checked, as was output from the same physical device, also battery and temperature levels, etc. There is no obvious cause for this discrepancy.

Comments and suggestions welcome and much needed!

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Latest settings under v1.12.1 (Used April 2025)

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Device ID : 24E144055E080133

Firmware : AudioMoth-Firmware-Basic (1.11.0)

Device time : 2025-04-18 09:27:17 (UTC+8)

Sample rate (Hz) : 192000

Gain : Medium

Sleep duration (s) : 5

Recording duration (s) : 3595

Active recording periods : 1

Recording period 1 : 17:45 - 07:00 (UTC+8)

First recording date : ----------

Last recording date : ----------

Filter : -

Trigger type : Amplitude

Threshold setting : 20%

Minimum trigger duration (s) : 1

Enable LED : Yes

Enable low-voltage cut-off : Yes

Enable battery level indication : Yes (NiMH/LiPo voltage range)

Always require acoustic chime : No

Use device ID in WAV file name : No

Use daily folder for WAV files : No

Disable 48Hz DC blocking filter : No

Enable energy saver mode : No

Enable low gain range : No

Enable magnetic switch : No

Enable GPS time setting : No

GPS fix before and after : -

GPS fix time (mins) : -

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Settings earlier under v1.9.1 (Config.txt dated 28/4/2024, same physical AudioMoth, not flashed)

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Device ID : 24E144055E080133

Firmware : AudioMoth-Firmware-Basic (1.8.1)

Time zone : UTC+8

Sample rate (Hz) : 192000

Gain : Medium

Sleep duration (s) : 5

Recording duration (s) : 3595

Active recording periods : 1

Recording period 1 : 09:15 - 23:30 (UTC)

Earliest recording time : ---------- --:--:--

Latest recording time : ---------- --:--:--

Filter : -

Trigger type : Amplitude

Threshold setting : 20%

Minimum trigger duration (s) : 1

Enable LED : Yes

Enable low-voltage cut-off : Yes

Enable battery level indication : Yes (NiMH/LiPo voltage range)

Always require acoustic chime : No

Use daily folder for WAV files : No

Disable 48Hz DC blocking filter : No

Enable energy saver mode : No

Enable low gain range : No

Enable magnetic switch : No

Enable GPS time setting : No

3 Comments

Alex Rogers

May 15

Hi,

There haven't been any changes to the core triggered recording code between 1.8.1 and 1.11.0, and the CONFIG.TXT file is reporting the settings correctly. The threshold is quite high so potentially a small loss in sensitivity from the microphone, or a reduction in the transparency of the acoustic vent, or the bats being further away, might result in the signal dropping below the threshold. For bats we typically use a 50kHz high-pass filter to remove low-frequency background noise and then set the threshold to 2% (or 1% in quiet environments) so it is just above the noise floor. Can you use the 'Summarise AudioMoth Files' option under the 'Process' menu in the Config App to generate a summary of one of the SD cards that seems light on content. We'll be able to check that the recordings weren't being cut short due to a low battery condition whilst recording. Alex

appz.tartness730

May 16

Replying to

Hi Alex

Thank you. Attached is the Summary for all 14 recorders over the five days. Note it is generated from the SSD which holds all the downloaded data from the SD cards; the actual Audiomoths are not available. It's a fantastic utility and saves time rather than having to look at file meta data on an ad hoc basis.

As for the threshold level, I did experiment with your suggested settings for bats before deciding on the protocol. The bat calls of interest in this study range from 12KHz to about 80KHz. After much experimentation the settings were deemed a good compromise, reducing disk space by around 80% to typically 100-200GB per session. We got 15GB this time!

Because the reduction in data collection occurred for all recording positions and Audiomoths, it is unlikely to be a problem with all the vents or even unusually distant bats, quiet trucks or loss of microphone sensitivity. The Audiomoths worked fine in February in a different location. It's very strange.

Thanks so much for your comments.

Richard

The battery voltages look fine. Some of the recordings are at different sample rates but that shouldn't make any difference as the amplitudes are normalised between sample rates. Is there any noticable difference in the recordings of bats that were captured?