Look under audio transitions / crossfade.
Ctrl+Shift+D for the default transition.
I have placed cursor at the join, gone ctrl shift D and got the Constant Power Crossfade, how do I make it dip to silence, as despite hitting enter to render , which then sees a video transition take effect, nothing happens to the sound.
When two clips are snapped together you need to trim of one frame to make it a single sided transition which you can place on the head or tail of the clip.
Hold down ALT and drag the audio of the clip 1 frame to the left/right, place the effect and strech the clip back to its place.
No wonder it didnt work when I tried doing that one sided transition with the clips touching....lol....boy, when you know the little tricks it sure helps a lot.
Along with the Audio Transition, one can also Keyframe the Audio Volume to achieve the "dip to silence."
I believe the Audio Transitions are buggy or dont work how they should if two audio clips are butted up to each other.
Theoretically one should be able to apply an audio transition such as Exponential Fade to the cut point then have it 'End at the Cut' or 'Start at the Cut'
It doesnt work and always crossfades unless worked around with a gap as described above.