If you are going to focus on sound devices, one of the clearest ways in which Shelley uses sound devices as you call them in this excellent sonnet is through alliteration, which is the name given for the literary term that denotes repetition of consonant sound at the beginning of words. There are a number of examples in this poem that are used to give emphasis to certain parts of the content.
Consider how the statue is described with its sneer of "cold command." The harshness of the "c" places importance on the harshness of the face of the statue. Likewise, the "boundless and bare" and "lone and level" sands that the traveller can see as far as he is able highlights the irony of the poem by exaggerating that sand is all that is left of Ozymandias's great empire and likewise his desire for immortality. From dust we come and to dust we will return.
In “Ozymandias,” Percy Shelley uses alliteration, as noted above. Like most poets, he also employs several other sound devices that are similar to alliteration.
In line four Shelley is describing the ruins of the statue of Ozymandias:
Half sunk a shattered visage lies, whose frown,
The sound device here is called “consonance.” Like alliteration, consonance uses consonant repetition to achieve its effect. However, unlike alliteration, consonance is not limited to using consonant sounds at the beginnings of words. In the line above, we have the “s” sound five times, twice as the first letter of a word, twice in the middle, and once at the end. Poets like to give the work an appealing sound, and this is one way they do it.
Shelley also uses a couple of different types of rhyme in his poem. Lines 1 and 3 end with the words “land” and “sand.” These words are called exact rhymes, because their ending sounds are exactly the same. However, lines 2 and 4 are a little different. They end with “stone” and “frown.” These words do not rhyme exactly—they sound similar, but a little different from each other. Rhymes like this are called by several names: slant, approximate, half-rhyme, and inexact. Poets use them when the words they want to use do not have an exact rhyme to pair with, or when they do not want their poem to sound too forced or regimented. Some poets, like Emily Dickinson, use them almost exclusively.