People eavesdropping on life underground

So interesting. I found the researcher's website: https://www.soundingsoil.ch/en/

There's a page with sound samples on a map: https://www.soundingsoil.ch/en/listen/

I tried finding a page where they described how they created the sensor, or some DIY instructions, maybe it was open, but I couldn't find anything. Only a reference that

> The «Institute for Computer Music and Sound Technology ICST»of the Zurich University of the Arts ZHdK first developed special soil sensors and adapted existing recording devices. This now allows us to listen to the soil and hear the crawling, scratching, communication sounds and eating noises of the animals underground.