Every sound in a scene adds to the story. Sounds create setting, mood, character, and can provide tension. Like endowed objects, there can be endowed sounds—a sound that means more than merely what it sounds like.
Keep a list of human nonverbal sounds, and a list of nonhuman sounds that might be heard, and use them in your writing. Here’s a start…
Human Nonverbal:
Cry of a baby
Sneeze
Burp
Whistle
Nonhuman:
Squealing tires
Gun shot
Wind through a maple tree in autumn
Glass breaking
Now for extra fun—especially if you are writing picture books—try to write the actual sound in words, making them onomatopoeic as possible. Margaret Wise Brown loved to do this in her books The Noisy Book and The Quiet Book. The sound of a truck going over a dirt road: burrippity burrp burrppity. Or the sound of a car siren: Err-u-ahh-err-u-ahh.
I love thinking of a sound as an endowed object! And the exercise is a great idea. I spend every Wednesday w/ my grandson (almost two) and he makes terrific sounds for non-human objects. The sound that a vehicle or animal makes becomes its name-e.g., a fire engine, for many months, was called a "Wheee" and a lion is a "RAWWWOR."