Great Alex, thank you very much for the quick reply. It must be a sd problem then. Cheers, Robert

Hi Alex, I was wondering whether the Audiomoth v.1.2.0 keeps working with the SPM0408LE5H-TB-6 from the v1.1.0 or you installed a different one. Thank you, Robert

Hi Alex, Did you finally have a look and how to use an external MEMS micro? I purchased a Knowles SPU0410LR5H-QB from Micbooster mounted in a PCB: https://micbooster.com/ultrasonic-microphones/146-ultrasonic-mic-board.html and soldered in a mono jack wire, attaching the + and out (signal) to the tip and the - to the sleeve. But the AM does not get any audio (no sound, just noise). Many thanks, Rob

Hi Edwin, I tested one device for each membrane and version, so one replicate. But keeping in mind all four membrane types showed poorer results on the AM 1.2.0., I think the differences between AM versions are real. I'll try to find some time and check the quality of the sonograms, but I don't think the noise would be the reason as all devices were recording simultaneously, so one noise would affect all devices. Cheers, Rob

@Alex Rogers The main issue with the EM258 is the max. freq being a bit too low for surveying european bats, for which you need to get up to 120kHz at least. But of course depending on the specific purpose of it might be enough. I'll be trying the external Knowles micro soon. Robert

@Wim van Dam Hi Wim, exactly, all have the same casing with a small hole in it, where the different membranes are.

Very interesting, andya. We haven't considered using the amplitude threshold option yet, but we'll certainly keep your results in mind when we do it. Also, it's surprising to see results vary depending on sampling rate! Important to say in the comparison done above all AM were set to the same configuration: 250kHz Sampling Rate, Medium Gain, No filters or threshold and sleep/recording duration of 0/3600s. SM4 were set to 256kHz, 0dB gain, and no trigger and file length of 3600s. So the observed differences are not due to different configurations. Cheers, Robert

Hi Wim, Sampling freq is 32kHz and gain High. I usually use Raven, with a FFT window of 587 in a 13" screen, 10 sec of window and up to 11kHz visible on the chart. Brightness and Contrast are set to 61 and 40 respectively. Cheers,

Thanks Davidlee for your response, that sounds more plausible!

Hi Andy, I didn't reply as I haven't got the chance to try it in a different laptop yet. Will do whenever I can! Cheers, Rob

Thanks Matthew for your response. The sound in the sonogram should not be real but an artifact, as we don't have bats calling at such low frequencies. Or perhaps that sampling you mention work similar to a frequency division system and that's why it looks and sounds so similar to calls recorded with this system?

Hi Matthew, Thanks for your reply. The audiomoth was housed in just a plastic zip bag. The pipistrelles I usually get around home are Soprano Pipistrelles (Pipistrellus pygmaeus), which usually emit calls from 50kHz to 60kHz, sometimes even lower. Also Common Pipistrelles (Pipistrellus pipistrellus) are around, which emit calls from c42 to c50kHz. Is there any physical event/process (e.g. echo?) that can create lower harmonics of an ultrasound? I rarely think so, but there is no other option I can think of! I don't really remember the gain settings I set, but I'd say it happens regardless this. Thank you, Rob

Hi Andy, Will try in a different laptop. Can you specify what USB driver from the list showing in the picture you mean? Thank you, Rob

This is what the USB ports show (sorry about the Spanish language, let me know if you need any translation): I've got a HDD and a mouse plugged via USB too. Thanks, Rob

Hi Andy, Thanks for your reply. Yes I have no issues configuring it with the old firmware. I've tried updating it with several USB cables as well, but with no luck. I will try that once I get the audiomoth back from the field next week. Thank you, Robert

Hi Julian, I was wondering how the small hole for the micro performed in the field. Did you eventually put cling film on it? Did you have any issues (leaking, puncturing) with it? Many thanks, Rob

Hi Adrià! In case it's of interest for you, we will be comparing Audiomoth with SM4 recorders for bird migration sampling in La Garrotxa next autumn. Not truly a bat comparison, but it'll hopefully helps anyway! Rob

@gordonc Hi Chris, Many thanks for your quick reply indeed. How do you set the parallel argument to use 4 cores? I've tried setting "parallel=2" (I'm using a i5 with two cores) with no difference in performance. Perhaps there is a different way to set the argument? We will be doing the ID manually as we don't have enough statistical knowledge (and time to learn this :( ) to set an autonomous ID process, but I've seen papers talking about machine learning processes including neural networks. Take a look at the following paper, which I understand it's a good review of the topic: https://onlinelibrary.wiley.com/doi/full/10.1111/jav.01447 I bet you have already consider it, but does your testing data have similar SNR ratio to your training data? I know this is a critical point when doing automatic bird call detection and ID. I understand you are also using R for the random forests. Are you focusing in only one type of bird call (e.g. one species)? Cheers, Rob

Hi gordonc, We will also be working with Audiomoth+warbleR package monitoring bird migration. How long does the autodetect takes to run through a night's recording (10-12h)? Ours need 5h to do so, which I it's a lot. Many thanks ! Rob