Example of film/tv scene where visual triggers audio only flashback?
I can't think of specific examples, but what I can "see and hear in my mind" is:


a single shot of the character who's having the flashback
the actor's face is reacting to the audio in the flashback
the camera slowly zooms or trucks in on the actor's face
sounds in the present-time scene have become quieter and/or muffled
the audio flashback may have an echo or reverb added to it
there may be visual flashbacks subtly transposed over the present-time shot