When you read poetry aloud, read it as though you were delivering the poem to an attentive audience. Why? Here are the three most important reasons you should read poetry aloud:
Poets design their poems to be read aloud. The earliest poetry was oral. People chanted it, sang it, recited it — and they still do. From its earliest forms to the poems being written today, poetry has kept its close alliance with speaking and singing.
The music of poetry — that is, its sounds and rhythms — isn't just for the eye and the mind, it's meant to be given voice. In fact, as they write, most poets imagine someone reading their poems aloud. Poetry is supposed to be a living thing, and poets write accordingly, with an audience in mind.
You'll experience the whole poem if you read it aloud. Poems read aloud are different animals from poems read silently. A big part of poetry is sound and rhythm — and the best way to get the full impact of these important elements is to put them into action by pronouncing them with your own throat, lungs, teeth, lips, and tongue.
Sound and rhythm don't exist just for their own sakes, either; they exist to give you pleasure (because humans naturally like music and rhythm in poetry) and lead you to the poem's meanings. Commas, spaces between words, line endings, and other pauses may hint at melancholy, hesitancy, or passion. Punctuation has its traditional functions (exclamations! questions? wistfulness . . .), and it often also is used in unexpected ways — or not used at all. You may miss all these signals if you don't read aloud.
You'll understand and remember more if you read aloud. Memory and understanding are everything. If you remember something and understand it, it takes up long-term residence inside your brain. And then you can use that knowledge as a building block to discover more and more about the world of poetry.