There are several sound devices that Hardy employs in his prophetic poem "Channel Firing," written in 1914, shortly before the beginning of World War I.
The poem begins in response to the gunnery practice heard in the English Channel. The second stanza has auditory imagery with the word howl. In the sixth stanza there is again this sound imagery with the mention of a trumpet being blown. The final stanza has the sound word roaring creating auditory imagery.
Rhyme and Rhythm
There is a uniformity to responses in sound as the poem is arranged into nine stanzas, each composed of a quatrain set in abab rhyme scheme, one of the most common forms of English poetry. This arrangement of rhythm--iambic tetrameter--and rhyme is suggestive of marching (da DUM da DUM da DUM da DUM).
The repetition of initial cosonant sounds, alliteration, speeds up a line of poetry. In the first stanza, the /g/ is repeated in the quick phrase, "great guns"; in the fourth stanza the second line moves quickly with the repetition of /r/: "Red war yet redder," while in the seventh stanza, the first line almost runs into the second line with the repetition of /w/: "I wonder,/Will the world..." Then in the fourth and ninth stanzas there is the repetition of /s/: "striving strong" and "starlit Stonehenge."
The repetition of vowel sounds makes for what is called "vowel rhyme." In stanza four the repetition of the short e creates this vowel rhyme in the phrase "Red war yet redder" as does the repetition of the short a in the phrase "Mad as Hatters."
This is also called slant rhyme, off rhyme, imperfect rhyme or half rhyme. It occurs when sounds are similar, but not exact. For instance, in the fifth stanza, with the rhyme scheme of the poem being abab, the alternating end words of "thing" and "threatening" are similar, but not exact in sound.
This sound device occurs when a word's sound is suggestive of its meaning. Such a word is "howl" in the fourth stanza: "the howl of the awakened dogs." In stanza nine, "roaring" also is an example of onomatopoeia.
"Modulation is a process by which the stress values of accents can be increased or decreased within a fixed metrical pattern." In the first line of stanza six: "Ha, ha. It will be warmer when"--Rather than follow iambic (a short stress followed by a longer one), as the rest of the poem does, the first two words have equal stress.