- Go to Track -> New Tracks... and click the "Software Instrument" at the top.
- In the "Instrument" picklist, go to "AU MIDI-controlled Effects" and select Unfiltered Audio G8, and click "Create."
- If you haven't already, add a separate audio track and add the audio that you want to be processed by the G8.
- Select the audio track, and in the Info pane, click on the Output button and select "No output."
- Then in your Instrument track, go into the G8 plugin window, and click the "Sidechain" picklist in the upper right, and select the name of your audio track.
- In the G8 plugin window, click the "MIDI" button to enable MIDI, and use the < > arrow buttons to select an appropriate midi note. The default is C3.
Now the audio in your audio track should be controlled by the MIDI data in your instrument track.