The use of words such as “thud” or “boom” that imitate the sounds made by the objects or actions they refer to.
Example: "Chug, chug, chug, the train went as it rumbled over the tracks."
"I'm getting married in the morning!
Ding dong! the bells are gonna chime."
(Lerner and Loewe, "Get Me to the Church on Time," My Fair Lady)