This program may be able to be used as a replacement for wireless microphone base stations at events. The software allows you to capture as many channels as your CPU can handle, within the active bandwidth of the RTL-SDR. There are also settings for tweaking the companding ratio and tau, deemphasis tau and FM deviation all of which affect the output audio and can be used to optimize the frequency response of the microphone.
The audio outputs directly to Jack audio which is an audio piping API, which simply routes the audio out to wherever you choose it to go.
When decoding a digital signal with an RTL-SDR the digital audio is usually piped from receiver software like SDR# via stereo mix or software like Virtual Audio Cable/VBCable into the decoding software. The decoding software expects a clean audio signal with the volume levels set not too loud, but also not too quiet. Usually this can be achieved by trial and error.
Many things you can do with rtl-sdr require piping the audio from SDR# or another software radio receiver into another program which is used to decode the audio. In Windows this can be achieved with stereo mix. This tutorial will show how to enable stereo mix.