(Contact) Microphone to record sound propagation in rocks?

Hi,
what kind of microphone can I use to record high quality sound from rocks (to check sound propagation through it)?

I assume contact microphones are preferred? But within that, which types? What specs?

Any help/suggestion is greatly appreciated! :slight_smile:

Thank you :slight_smile:

Apparently geophones mostly operate below 100Hz,
that’s not “high quality” enough for speech or music, just bassy thumps.

Thank you @Trebor, I know about them but are totally unsuitable for exactly the reasons you mention. Also they are for the ground not to “stick” on rocks.
What I am looking for (no idea if they exist) are very sensitive microphone (small ones) to “stick” onto a rock or a stone on a building.

The type that (most likely) needs some kind of acoustic couplant (coupling material).

So most likely they are some piezo-like mic / transducer with the front face exposed so it can be put in touch (glued?) with the surface.

Then the rock excitation is then done with small transducer or a small hammer.

Any knowledge of anything along these lines?

Thank you :slight_smile:

No idea if this helps: decades ago I got me a simple piezo transducer to experiment with picking up sound from the body of my guitar. It was a dime-size, very thin thingy with a shielded cable dangling, to be connected to an amplifier.
The tricky part would be to get this in solid contact with the rock, without losing higher frequencies (as result of a elastic coupling). The transducer itself should be good enough for picking up higher frequencies if made for guitar pickup.
Just my 5 cents…