The Recovered Audio

Recall that an inductor blocks higher frequencies while allowing low frequencies through so, in the top picture, the addition of the RF Coil has effectively blocked the 10.7MHz signal leaving a clean audio signal - but, it is still a DC voltage and unsuitable for an audio amplifier.

With the addition of a large Audio Capacitor, the low frequency audio can pass through but the DC 'component' of the signal is removed.

The bottom picture shows the final output - a fully cleaned up, AC audio signal suitable for feeding an audio amplifier.