How does Donne use poetic techniques to convey emotion in 'Batter My Heart'?

Form and metre are handled in conjunction with imagery to convey the intense spiritual anxieties that are explored in 'Batter My Heart' and Donne's other Holy Sonnets. The speaker's command to 'Batter' his heart is trochaic where an iambic opening would be more common. Donne's subversion of conventional Petrarchan sonnet metre increases the effect of the imperative verb 'batter', which is strikingly onomatopoeic in itself, and establishes the speaker's desire for spiritual reshaping; a desire which is further conveyed by the string of monosyllabic, alliterative verbs in the fourth line of the octet. A trochaic foot again is used to open the fifth line ('I,'), accentuating the comparison to a 'usurp'd town', invoking the sin and villainy of Sodom and Gomorrah. This emphasises the speaker's place as the centre of the poem, in yearning for divine intervention, which is carried through to the closing rhyming couplet, where the speaker fears that he shall never be 'free', or his soul 'chaste', unless God 'ravishes' him.