Bradbury employs poetic devices in his story "A Sound of Thunder." For one thing, he utilizes ironies: The reversal of hunted/hunter, the aplomb/cowardice of Eckels, the insignificance/monumental importance of a single butterfly.
In addition to these ironies, Bradbury employs metaphor. "The sound of thunder" is first the massive movement of the Tyrannosaurus rex and at the end of the story, the echoing of both the memory of this dinosaur and the shot from the rifle of Travis.
Paradox is another poetic device in use by Bradbury. He write of the "gliding ballet step" of the dinosaur, and it is "balanced for its ten-tons." Its "body twitched even while the monster itself did not move. Of course, the concept of going forward to the past in the time machine is a paradox. And, the theme is presented in this very paradox. Everything in the past affects everything in the present and in the future.
As T. S. Eliot wrote,
Time present and time past/Are both perhaps present in time future,/And time future contained in time past.
As in most of his work, Bradbury writes "A Sound of Thunder" in a lyrical style, the solidity of prose transformed into the liquid of poetry—while he still retains all the conventions of a plotted short story with characters, theme, and even an ironic twist. Bradbury writes science fiction, but we do not read him for a prosaic quality of describing in minute detail the physics of how a time machine might really work or for a hard analysis of the chemical compounds in the air millions of years past. Instead, we read Bradbury for his use of language, his ability to convey an atmosphere through imagery and metaphor, his imagination, and his ability to communicate the breathtaking and the ephemeral through the emotionally charged subjectivity of a character.
"A Sound of Thunder," a story of time travel gone awry, opens with an image:
The sign on the wall seemed to quaver under a film of sliding warm water.
The language conveys the fragility of time itself, which makes reality provisional, but rather Bradbury uses the imagery of water, in which a sign, something seemingly solid and authoritative, is shown as impossible to grasp as water. With this image, Bradbury begins the process of establishing his theme: the hubris (pride) of humans in thinking they can master time, use history as they want to, for their pleasure, and without consequences.
The lyrical language continues as the story unfolds through Eckels' subjective sensory and emotional impressions, which have the quality of poetry. In the quote below there is imagery (use of the five senses, in this case sight and sound) and simile in the comparison of the sound of the machine to a bonfire burning time:
Eckels glanced across the vast office at a mass and tangle, a snaking and humming of wires and steel boxes, at an aurora that flickered now orange, now silver, now blue. There was a sound like a gigantic bonfire burning all of Time, all the years and all the parchment calendars, all the hours piled high and set aflame.
This lyricism carries us through the wonder and terror of time travel in the story and back to the present, where everything is altered. Near the end, Eckels realizes that he has killed a butterfly during his time travel, described with imagery ("golden") and alliteration ("scrabbled" and "shaking"):
He scrabbled at the golden butterfly with shaking fingers.
And at the end, the irony of the title becomes apparent, but his death, described with a metaphor as he is shot ("a sound of thunder") has a lyrical, subjective quality:
Eyes shut, he waited, shivering. He heard Travis breathe loud in the room; he heard Travis shift his rifle, click the safety catch, and raise the weapon.
There was a sound of thunder.