Signal in an Audio Cable
In a matched propagation conductor, the signal's speed is matched to the speed of the dielectric and like the boat illustrated below, leaves little wake turbulence.
Signal waveform of Matched Propagation Conductor,
viewed at -56db from the fundamental pulse
In a standard conductor, the signal's speed exceeds the speed of the dielectric creating turbulence that continues long after the signal has passed.
Signal waveform of Standard Conductor,
viewed at -56db from the fundamental pulse