How to record pure vocals with AU requires post-production, so you need unaccompanied vocals, how to record them and how to extract them.

Plug the microphone and earphone (or headset) into the corresponding sockets respectively, and debug the volume of the earphone and microphone. In multi-track: Insert your accompaniment into track 1, press the R button in front of track 2, and then press the Record button on the control panel below to start recording. After recording, double-click the second track (just recorded voice) with the left mouse button, and the software will automatically jump to the monorail window. Click File-Save As to save clean sound. Of course, other processing can be done at this time, and then multiple tracks can be inserted and mixed with accompaniment.