In the underwater case the self noise of AudioMoth 1.1 is amplified. The noise appears as artifacts in the recording. The artifacts can be seen as high frequency low amplitude impulses representing SD card writes. The noise can be reduced by using good quality Lithium batteries and low energy SD cards. If you are recording at a lower sample rates <48kHz, the noise generally doesn't appear.

Hi Carly, Yes, there is little to no global microcontroller stock at the moment, suppliers are estimating that AudioMoth chips will be back by 2023. We can't give accurate estimates, but are hopeful for a new batch of AudioMoths by early next year with the availability of the new supply. We will prioritise AudioMoth 1.2.0 manufacture when the chip supplies do come back. For cases, GroupGets and LabMaker have plenty of the terrestrial and underwater versions if you need them. Thanks,

Hi Alison, I'd be happy to help. What advice do you need?

Hi Douglas, You can find the datasheet for AudioMoth Dev on the website here. The connector pinouts are shown in Figure 1 and described on page 3. Thanks, Andy

The metadata will be there, but it may take a while to load on Mac if you have many large files.

The soldering looks good to me. Do both the modified SPM0204UD5 with external circuit and Animal sound Labs ME4-em have the same issue. Does the AudioMoth external mic work with any other electret condenser microphones you have? Might need the wiring you used to connect these mics up to the 3.5mm jack to diagnose further. For diagnostics, @Alex Rogers has a nice test - here's the video from twitter. When AudioMoth switches between internal and external microphone, you can see it closing the current file and starting a new file each time the microphone is changed, this works best when recording at 192kHz. You can see the files close whenever the LED stops flashing. Does your unit do this?

Glad we got to the bottom of it. Andy

Hi Richard, That's good to know. If that's the case it's most probably the battery. In the WAV comments in the shorter recordings it should state the reason for stopping as low battery voltage. The 0KB files result when the AudioMoth has opened a file but was not able to close it. This normally happens due to the battery running down during a recording. The 'Enable low-voltage cut-off' option attempts to prevent this by stopping recordings early due to the the low voltage but it is still possible for the write to fail at low voltages depending on the type of SD card.

12V is pushing the AudioMoth power regulator quite hard and for longer recordings a 12V supply will cause high temperatures of >54 degrees C above ambient at the regulator, possibly causing it to stop working at high ambient temperatures. Have you considered using a lower voltage battery? 6V lantern batteries would work well.

Hi Richard, I have a feeling this could be an SD card issue. Are you deleting the files from the SD card each night? As SD cards fill they take longer to open and close files. It might be that your SD card is getting full and needs reformatting. Let us know if that fixes it, Andy

How often do they loose power? What recording schedule and configurations are you using? Could you post the CONFIG.TXT file.

Hi David, It might be worth re-flashing firmware 1.6.0 again, however, when you do it make sure the batteries are removed during the flash process? The device will need a power cycle after re-flash too so make sure the USB is disconnected before putting the batteries back in. Let us know if this solves the issue. Andy

For step 4 - what do the LEDs do when you switch between CUSTOM and DEFAULT? Do your other units work okay?

Are there any signs of weather damage on the device, such as water ingress or corrosion?

Hi Silvy, I'll try my best to answer these for you. (i) the sensitivity of the acoustic transducer, which defines how much voltage is generated per unit of sound pressure. The MEMS mic on AudioMoth 1.1.0 has a sensitivity of -18 dBV/Pa, this is measured when used together with the MEMS output amplifier set to a gain of 10. Here is the MEMS mic data sheet for your reference. (ii) the amount of additional voltage gain applied by the pre-amplifier. At the mid gain setting this is 15, below are the gain values of the other gain settings corresponding to the radio buttons in the AudioMoth Configuration App. Gain 0 Min 4.33 1 7 2 Med 15 3 25.1 4 Max 30 (iii) the ADC input voltage which corresponds to the maximum amplitude that can be represented in the audio files. On AudioMoth 1.1.0 the full 16-bit 0 to 65535 amplitude range corresponds to 0V to 3.3V. I hope this helps, Andy

Yep @Edwin Houwertjes is correct. AudioMoth 1.0.0 and 1.1.0 use the SPM0408LE5H - datasheet here. AudioMoth 1.2.0 uses the SPU0410LR5H - datasheet here.

The cases are available for immediate purchase on the GroupGets store and LabMaker store. GroupGets add the case as an optional extra on AudioMoth campaigns at a reduced cost.

The IPX7 case is completely waterproof so should be fine if the case is closed in a dry environment.

My concern with AudioMoth in a plastic bag in cold environments is that you will probably get condensation issues inside the bag, which would lead to moisture damage on the hardware and device failure. Might be worth looking at adding moisture absorbing sachets, either way you wouldn't want to leave them out for too long in a thin grip sealed bag during winter.

Hi Matyáš The main constraint with AudioMoth at low temperatures is the type of battery chemistry you use. You'll probably have issues with rechargeable batteries at that temperature, but lithium batteries should be okay. The battery data sheet should give you a temperature range. Thanks, Andy