What does a poet do to create a specific dominant impression on a reader?
Poets can use any of a variety of literary devices and techniques to shape a specific dominant impression on a reader. The choice of which techniques are used in a given poem depends upon the theme of the poem and the effect the poet wants to create.
A poet may the words used in writing a poem to create a desired impression when the poem is read or heard. Alliteration is a technique that uses the same sound at the beginning of multiple words. Assonance refers to creating rhymes within words by using the same vowel sounds repeatedly. Onomatopoeia uses words that sound like what they mean. Rhyming sounds at the ends of words and the rhythm of the words used in poems also contribute to the impression created when a poem is read aloud. Consider "The Raven" by Edgar Allan Poe, which uses onomatopoeia, rhyme, rhythm and vivid symbolic word choices.
While I nodded, nearly napping, suddenly there came a tapping, As of someone gently rapping, rapping at my chamber door. "Tis some visitor," I muttered, "tapping at my chamber door - Only this, and nothing more."
Poems may utilize specialized fonts or spacing or arrangement on a page to create a mindset or impression in the reader.
Poets have a variety of devices at their dieposal - they have to since they have to be much more concise and have less "time" so-to-speak to convey the meaning they want. Specifically, sentence fluency and word choice are wonderful ways to convey an impression.
Sentence fluency can be used to create either a languid, relaxed feel (think a longer, smooth sentence = long, rolling waves on the ocean), or a frantic, urgent feel (short, choppy sentences = choppy, unsettling waves).
Word choice includes many areas including specific word choice (I have a much better understanding of the poem if I know the man "dashed" vs. "went" or "ran") and imagery and figurative language. Using more than one sense to paint a picture draws the reader in more completely. I get a better impression of, for example, the despair felt by someone stranded out in the rain after a car accident if I can not only see the rain, but hear the sizzle of the cold rain drops on the still-ticking engine, feel the icy pricks as it hits my face, smell the damp, earthy smell as it mixes with gasoline fumes and the smell of rubber and tar on the road.