Analysis: Sound Check
The speaker is obsessed with hearing in "London." Three of the poem's four stanzas, for example, say something about sound or hearing. Cries, curses, voices, "mind-forg'd manacles," and sighs all make up the sound-scape of London. The speaker doesn't just list things, however; he does his best to make sure we get a sense of what these things sound like, a sense of what London sounds like.
The most powerful way in which the speaker achieves this is by making us feel claustrophobic, figuratively speaking. "London" is a poem all about constriction ("charter'd), confinement, repression, slavery—those sorts of things. The streets seem narrow and controlled, ditto the Thames, and everybody is enslaved by "mind-forg'd manacles."
Well, guess what? The poem's language is narrow and confined too. Did you notice all the repetition? Words are repeated like crazy ("charter'd," "infant," "cry," "marks," "hear") as are letters too (note all the S sounds in lines 9-12, or the "ear" sound in lines 13-16, or the R sounds in lines 5-8). Alliteration is a frequent visitor ("Chimney […] Church"), and there's some textbook anaphora going on in lines 5-8 ("in every"). The bottom line: repetition is everywhere, especially in the sounds of this poem, which makes us feel as though the poem is somehow restricted or limited, sonically speaking, just like London.
At other times, the speaker will flirt with onomatopoeia to try to give us a better sense of the shock he experiences while walking around London. Take lines 13-15 as an example: "But most thro' midnight streets I hear / How the youthful Harlot's curse / Blasts the new-born Infant's tear." Notice how the word "blast" comes busting in right at the beginning of line 15. The word "blast" itself almost kind of sounds like a blast, and its placement at the very beginning of the line creates the effect of a word "blasting" on our senses. Can you find other examples of this kind of effect?