The few seconds the turn signal in you car blinks in sync with the car in front of you. The symphony comes from the ticking sound which provides the necessary audio to match the visuals. Though very short in duration, the symphony causes so much intrigue in those who experience it that they desperately anticipate its rare but occasional second occurrence before traffic ahead starts moving once more.
Passenger: Dude why are you smiling at the light from the car in front you?
Driver: *oblivious to surroundings due to absolute immersion in blink symphony*
Passenger: Yo there are no cars coming, mooooove.