Poems often utilize many devices to be effective and successful. Three related terms referring to sound in poetry are alliteration, assonance, and consonance. These three terms are often confused for one another, or used in place of one another. Though they are related, they are quite different.
Let’s look at them separately:
Alliteration is the repetition of consonants within words in close proximity. Alliteration generally refers to sounds at the start of a word. Here are two literary examples:
Beowulf was written in Old English and contains many lines of alliteration:
feasceaft funden; he þæs frofre gebad,
weox under wolcnum, weorþ-myndum þah
In the first line, the letter “f” is used in repetition, and the same with “w” in the second line.
In Gerard Manley Hopkins’s “Pied Beauty”:
Glory be to God for dappled things…
Landscapes plotted and pieced–fold, fallow and plough;
And áll trádes, their gear and tackle and trim.
The letter “g” is used in repetition in the first line, “p” and “f” in the second line, and “t” in the third line.
In one more example, Shakespeare parodies alliteration in Peter Quince’s Prologue in A Midsummer Night’s Dream:
Whereat, with blade, with bloody blameful blade,
He bravely breach’d his boiling bloody breast.
Assonance is the repetition of vowel-sounds within non-rhyming words.
In Poe’s, “Bells” he uses assonance of the vowel “e:”
Hear the mellow wedding bells.
Assonance of the vowel “u” used by Robert Louis Stevenson:
The crumbling thunder of seas
Consonance is the repetition of consonant sounds within words. Consonance is very similar to alliteration, but the distinction between the two lies in the placement of the sounds. If the repeated sound is at the start of the words, it is alliteration. If it is anywhere else, it is consonance. In most cases, consonance refers to the end sound (like “nk” in blank and think
Consonance in “The Silken Tent” by Robert Frost:
“as in guys she gently sways at ease”
Comparing Alliteration, Assonance and Consonance:
There is an example of all three of these terms in one line of the poem, “The Raven,” written by Edgar Allan Poe:
And the silken sad uncertain rustling of each purple curtain
This line clearly contains all three, and can show the difference between assonance, consonance and alliteration.
Assonance is the repetition of the ur sound in “purple” and “curtain.”
Consonance is the repetition of the s sound within “uncertain” and “rustling.”
Alliteration is the repetition of the s sound at the start of “silked” and “sad.”
These terms are very closely related, though the distinction between them comes in determining vowels versus consonants, and then placement within the words.