I guess a simpler alternative could be to ‘point’ it at internet radio streams, broadcast from different countries?

Using a magnetometer means that it doesn’t need to be re-calibrated if it is moved to a new location. It “just works” (assuming no magnetic interference…)

It certainly has ancestry of weird and wonderful listening devices!

It would certainly be an interesting twist. Perhaps a comment on surveillance society!

In another direction, the satellite Pis could feature a non-audio sensor – e.g. if each one had a Geiger counter, they could contribute to a vista of clicks.

A potentiometer would have given some good accuracy, but I was a little concerned that solution would introduce a fragile (snappable) component – and I wasn’t sure how to seat it within the piece.

The magnetometer has it’s own challenges (especially around interpreting the data) but worked out well in the end.

Another fallback option I considered was to have a Pi camera pointing up from the base watching a coloured spot on the base of the cones- though that might have involved some coding complexity and likely been heavy on the processor. I’m glad I didn’t have to go there! :)

Maybe it’s possible to “smudge” the audio so speech isn’t intelligible, in case of unsavoury language or verbal indiscretion near the microphones.

This is an interesting idea – I’d love to see it recording and delivering live sound from other cities, maybe even other countries, in whichever direction.

Not a small task though!

Some clever work, I would like to try this. Now show us that Nintendo Guitar again haha :D