Nice demo of cross talk. Last year I fixed a problem in our glider where the microphone wires were not completely shielded, as in your demo, and were picking up signal from the radio speaker wires, also not completely shielded. The result was intermittently the radio would squeal during transmit due to feedback from the speaker back into the microphone. It was intermittent due to the wires shifting slightly every time the canopy opened/closed. Shielding both the speaker and microphone wires fixed the problem.

Rich L.