The AI program for recognizing bird vocalizations, Merlin, is available on your phone. It's really changed how birding is done. It will detect and identify the species of birds in real time as you are walking around, often before you yourself recognize them (if you are even able to).
I've found it to be quite accurate here in upstate NY, with a few recognizable exceptions. In particular, sometimes it seems to think it's hearing a blue-headed vireo when a red-eyed vireo is singing. Also, it sometimes misreports yellow-rumped warblers.
How about an amplifier connected directly into the Merlin bird app’s always listening mode. You don’t even have to review the files. You’ll just get a list of all the birds it has picked up. Birdnet is probably the same API Merlin uses.
I'd be interested to hear more about this. I came close to working on a similar setup but the primary limitations were power and data connections. We figured we'd either need a manual rotation of batteries and storage, or maybe buried PoE to handle both. We never got past the initial concept
Our slow-but-steady concept is down the batteries and storage fork in the road you lay out. Some areas are too remote for infrastructure, so we just revisit and change batteries and cards periodically.
We use dedicated trailcam-like recorders that drop `.wav` files to a 256GB SD card for a few months on four "C" size batteries. Several sites are very remote (islands separated from mainland by several miles), and recordings are scheduled for only 6 hours per day according to the study's focus.
It's using a cheap (0.40c) sound card, but personally I choose to have high quality mics (primo em272 mic capsules, used in high quality parabolic systems.
However, there's nothing to stop you using < 10.00 euro microphones.
sbts-aru writes the files to an SD card so you don't need a whole running windows for this.
Also, it passes all the audio through real time jackd, so while it's writing files you can also have an addition consumer running a real time matchin algorithm on it. If you use a Pi 4 or 5 you would be able to also do that at the same time on the same Pi as is recording.
PoE works better (cheaper, higher bandwidth, differential signalling for higher EMI resistance, readily shared, etc.). Plastic covers are ~free (splash out and deploy duct tape if necessary). MEMS mic -> I2C -> cheap MCU -> ethernet. Theory: Capture digitally, and send the data - forget XLR and other expensive analog 'professional' fancabulation[0]. [0] https://www.youtube.com/watch?v=Ac7G7xOG2Ag
POE very easily tends to inject noise into microphone inputs. If you run a Raspberry Pi for example with POE you get that. This can be fixed by using a power conditioning hat and a POE splitter but now the costs are really increasing.
I suspect that though the author describes running a USB cable to the house, he may be preparing it for remote operation.
(If you can count on it being next to a house where you can run a USB cable, you could also just power it off USB and skip the battery, right? So the battery must be designed in for a reason.)
The mic is a condenser mic, so a pre-amp is needed, XLR or not.
Cheap mics tend to be single-ended things without the balancing transformer or amplifier, so that would all be extra cost. XLR connectors and cables are more expensive. You'd want to go into some audio interface with XLR jacks which is also more expensive.
'remote' also means you can set up networks of them to cover your area. Just dump a bucket every n meters, and spend a few hours driving around every few weeks to harvest the data & swap out batteries.
Are there microphones that would let you "listen" to bats? We have bats fly around our house at dusk, it would be interesting to know what they "say", especially when two of them come close (unclear whether that's intentional or not).
Reading wikipedia "Bats emit calls from about 12 kHz to 160 kHz, but the upper frequencies in this range are rapidly absorbed in air.", so I guess the Primo wouldn't be suitable for the higher bat freqs.
If you want to pay more you can also get Pettersen ultrasonic microphones. These have a USB microphone and will also work with my sbts-aru recorder. Which means you could in principle also geolocate where the bats are.
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But it it's not 100% accurate and currently focuses on birds from Canada, the US, and Europe.
Battery and sound card and preamplifier outdoors to then run a USB cable out to it seems like a bit of a faff.
https://github.com/hcfman/sbts-aru
It's using a cheap (0.40c) sound card, but personally I choose to have high quality mics (primo em272 mic capsules, used in high quality parabolic systems.
However, there's nothing to stop you using < 10.00 euro microphones.
Also, it passes all the audio through real time jackd, so while it's writing files you can also have an addition consumer running a real time matchin algorithm on it. If you use a Pi 4 or 5 you would be able to also do that at the same time on the same Pi as is recording.
https://acousticnature.com/journal/how-to-make-diy-microphon...
But it works.
(If you can count on it being next to a house where you can run a USB cable, you could also just power it off USB and skip the battery, right? So the battery must be designed in for a reason.)
The mic is a condenser mic, so a pre-amp is needed, XLR or not.
Cheap mics tend to be single-ended things without the balancing transformer or amplifier, so that would all be extra cost. XLR connectors and cables are more expensive. You'd want to go into some audio interface with XLR jacks which is also more expensive.
See - https://zachpoff.com/resources/cheap-microphones-for-ultraso...
Reading wikipedia "Bats emit calls from about 12 kHz to 160 kHz, but the upper frequencies in this range are rapidly absorbed in air.", so I guess the Primo wouldn't be suitable for the higher bat freqs.
https://www.omenie.com/pipistrelle.html
If you want to pay more you can also get Pettersen ultrasonic microphones. These have a USB microphone and will also work with my sbts-aru recorder. Which means you could in principle also geolocate where the bats are.