Onomatopoeia, a word that is, itself, hard to pronounce, relies on the sounds of words to make the magic happen. I used this tool in a tiny bit of a TWCBC ad that I won for my bike shop. They asked for a quote, and I took advantage of two words that carry this trope: Ring and Cha-ching.
Ring is a word that sounds like a bell (or cell) ringing. We instantly understand that "Ring! Ring!" means someone is calling my store, perhaps to learn more about the bikes. Capping the line with "Cha-ching!" sounds so much like a cash register that it has become cliché for making money.
I submitted this line along with a few others (always hedging my bets), and this is what they chose. I believe they picked it for functional reasons, as advertisers. They wanted a quick line that would resonate with readers, play in their heads, and be memorable when it comes time to make their own choices for cable. It's a great, useful tool to keep handy for those times when you want to grab a reader quickly, perhaps with a little humor. And, of course, it helps to throw in another great trope, rhyme, to drive it home completely.
Dictionary.com defines onomatopoeia, in part, as:
the formation of a word, as cuckoo, meow, honk, or boom, by imitation of a sound made by or associated with its referent.
the use of imitative and naturally suggestive words for rhetorical, dramatic, or poetic effect.
An excellent writing teacher I knew advised her class to "Say complicated things simply, and simple things with artistry." So, depending on the type of project I'm creating, I choose my palette of colors carefully. It's a balance between clarity and artistry. A favorite way to add shadows and create depth in a story is to add onomatopoeia, words brought to life through their sounds.
I wouldn't fill a general prose page with obvious onomatopoeia just for a noisy effect, unless I were perhaps writing about a blind person who depends on sounds to represents images. The "snap" of a twig to a blind person would be a much more compelling than a scene stuffed with sound words when the character could see imagery. Of course, sounds, sights, smells, touch (pressure, heat, pain, itch, etc.) and even taste can add something to your writing. On the other hand, I have had plenty of fun composing works with more subtle forms of onomatopoeia.
When describing the moment a bicycle tire goes flat, I could write:
She glided along the side of the path, coming too close to a jagged rock outcropping that snagged her tire's whitewall. Boom! Goosh! SSSSSssssss! The tire blowout could be heard down the street where bystanders paused to gawk, mouths open, as the rider's body slammed the pavement while Green Slime oozed from the tire's gash. The last bit of air bubbled out with the slime and then all went still.
With this example, look past the obvious "Boom" words to see that numerous "sound sensitive" words subtly help the scene. Even the bystanders gawking with open mouths is alive with imagery created by the sound of the word. Say, "gawk" and see how your mouth opens. Can you count the number of words in this paragraph that offer some onomatopoeia? You might be surprised upon close inspection.