Lay down the music at a constant, normal level.
Then use the Ducker feature to dip it when there's speech on another track. OPTIONS | AUDIO. Adjustment takes experimentation.
Right-click the music track and choose
.
http://help.nchsoftware.com/help/en/videopad/win/effect_autoducking.html
Or manually split out the speech areas on the music track, then double-click the music track in those areas. The waveform will appear in the preview window.
Plot a graph by dragging the blue line to create keyframes (represented by squares/dots). Here, music dips, stays steady for a time, then returns to normal level.
