I use the tried-and-true
manual method for adjusting volume of music behind my voice. Using PD's audio mixing "room" I just click on the audio track for the music, creating a point at where the existing level will be attenuated, step forward a few frames, click again and, at that point, either manually pull down the level, or type in a new "value" in the space above the "slider" level control. Where I want the music to go back to its original level(after my comment), I follow the same proceedure, click once on audio timeline, step forward a few frames, click again and at that point, either drag up to original level, or type in original level's value in the box above the slider., Might be time-consuming but it ensures you get the wanted effect.