Rhythm :]

Definition: the basic rhythmic unit in a piece of music.

Significance: make listeners or reader feel the story easier.

Example:

I hear the sound I love, the song of the human voice, 
I hear all sounds running together, combined, fused, or following, 
Sounds of the city and sounds out of the city, sounds of the day and night,
Talkative young ones to those that like them, the loud laugh of work-people at their meals...