Contact microphone sound test
This is the first prototype of a tin can with a contact mic attached. The audio is water dripping from a irrigation drip emitter into the can.
The sound it produces reminds me of the very low frequency (VLF) radio atmospheric signals (sferics) "tweeks". Tweeks are produced when sferics from a storm travels thousands of kilometers by boucing off the ionosphere. The sferics produce tweeks when the low frequencies travel slower than the faster frequencies causing a slight offset in time. Some examples of tweeks can be heard here at Spaceweather.comContact mic tin can by veryphatic