BirdNet-Pi: USB audio module testing

I've bought a couple more modules

so thought I'd do some tests to compare performance.

This post concerns the use of USB audio modules in connection with miniature electret microphone capsules.

BirdNet-Pi: more thoughts on microphones & audio

There's a lot of talk on the Github Discussions page about microphone quality.

So naturally I have been giving the matter some consideration and have conducted a few simple checks.

BirdNet-Pi: portable operation, mics & bird dogs

Its been an interesting couple of weeks.

I've experimented quite a bit with my BirdNET-Pi system and even built a second system.

Bat Call Logger: Wolfson audio card frequency response

Having got my Wolfson Audio card working happily with a Raspberry Pi 2, I decided to try and check the frequency response.

As this card is described as a 'audio card' and the only figures I've seen relate to the audible range, I didn't have high expectations regarding its use in my Bat Call Logger.

Anyway, to find the answer, it was just a question of setting up some test gear and running a few checks.

Bat Detector: electret microphones

Building your own Bat Detector is a relatively easy electronics construction project.

The tricky bit can be locating a suitable transducer or microphone that has a useful frequency response into the ultrasonic range used by common bats.

During the last few weeks I have been testing a number of devices, and here are my notes.