Apple Final Cut Pro 7 - Manual (Page 953)

The following example shows a sequence with one video track and three audio tracks.
A video montage is edited into track V1, with accompanying music edited into tracks A1
and A2. To record to track A3, you need to connect the a2 Source control to the track A3
Destination control.
Connect the a2 Source
control to the A3
Destination control. Before
The newly recorded audio clip
is placed in track A3. After
If the track connected to the a2 Source control already contains audio, audio recorded
with the Voice Over tool is placed in the audio track directly below. If no audio track
currently exists below the track connected to the a2 Source control, one is created.
953 Chapter 58 Using the Voice Over Tool