Hello, I have used acoustic monitoring for bat studies before, but this is my first time using Audiomoth, and using a device that can record both human-audible sound and bat vocalizations. As such, it's been a learning experience to dial in my device settings so that they are optimized for bats.
I am currently trying to use the device in Michigan, where most bats have calls in the 25-75 khz range. A couple species of interest have the strongest part of their calls (characteristic frequency) in the 40-45 khz range.
I currently have the device configured as follows in an attempt to get mostly bats:
![](https://static.wixstatic.com/media/2bdf9f_0f577cd71a624a9c9c990467a448ea09~mv2.png/v1/fill/w_49,h_58,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/2bdf9f_0f577cd71a624a9c9c990467a448ea09~mv2.png)
![](https://static.wixstatic.com/media/2bdf9f_38e03a4651054eafb56fff5b95923e87~mv2.png/v1/fill/w_49,h_59,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/2bdf9f_38e03a4651054eafb56fff5b95923e87~mv2.png)
![](https://static.wixstatic.com/media/2bdf9f_9e09fd7913eb4fda9646b3e9a293f214~mv2.png/v1/fill/w_49,h_59,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/2bdf9f_9e09fd7913eb4fda9646b3e9a293f214~mv2.png)
And I am recording bats, so that's good! But I'm also recording lots of non-target noise. I get a lot of recordings that look like this (wav file also attached).
![](https://static.wixstatic.com/media/2bdf9f_38e07c757b6e4d1082414edce994cb39~mv2.png/v1/fill/w_49,h_31,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/2bdf9f_38e07c757b6e4d1082414edce994cb39~mv2.png)
Which I'm assuming is just orthopteran noise. Those pesky orthoptera! Anyway, there is rather a lot of it, and I'm wondering if anyone has suggestions to dial in my settings (or for settings when expanding/splitting files) so that I can reduce this stuff and save fewer noise files? I've only done passive acoustic monitoring with Anabats, and that was a long, long time ago, but I don't recall getting quite so many noise files. Thanks for any thoughts!
Try experimenting with these files in AudioMoth Play - https://play.openacousticdevices.info. You can try out the filter settings on the recordings and check their effect. Using the recording above, if I increase the window length to 32 samples, this makes the frequency band narrower and it no longer triggers on the orthoptera. It will likely still trigger on the bats at a slightly high frequency.