What property allows an RF bypass capacitor to have little effect on an audio circuit?

Capacitive reactance decreases as frequency increases, which means a capacitor presents a much higher opposition (reactance) to lower frequencies like audio signals. While an RF bypass capacitor easily passes high-frequency RF to ground, its high reactance at audio frequencies makes it act like an open circuit to the desired audio signals. This ensures the audio signals continue along their intended path rather than being shunted to ground.