What literary device creates sound effects to mimic the thing it describes, as in "cuckoo" or "meow"?

The correct answer is onomatopoeia, which refers to words that phonetically imitate, resemble, or suggest the sound that they describe. In your examples, "cuckoo" imitates the sound of a cuckoo bird, while "meow" mimics the sound made by a cat. Both of these words are formed to replicate the actual noises, enhancing the reader's experience by providing a vivid auditory element to the description.

In contrast, alliteration is the repetition of the same initial consonant sounds in a series of words, often used for rhythmic effect rather than sound imitation. Metaphor and simile are both figures of speech designed to make comparisons, with metaphor suggesting one thing is another directly, while simile uses "like" or "as" to highlight similarities between two different things. Neither of these literary devices creates sound effects.