One need not be a Chamber- to be Haunted: Structure & Language Techniques

Structure

Dickinson employs a quatrain structure in the poem, this regularity creating an insistent and relentless tone which parallels the infiltration of the mind by fear.
Despite the regularity of the quatrains, Dickinson’s characteristic ‘slant’ rhymes give the poem an uncanny feel which further enhances the themes of the unseen and internal ‘haunting’.

Language Techniques

Alliteration: Dickinson uses alliteration, such as in ‘cool consternation’. This enhances the rhythm and musicality of the poem, but the strong, hard ‘c’ sound could also be seen to underline the harshness and terror of the internal haunting.
Metaphor: The concept of the ‘brain’ being wider than the ‘sky’ and ‘deeper’ than the sea is used to elevate and intensify the power of human imagination and emotion.
Personification: The use of phrases like ‘an armed man’ allows Dickinson to personify abstract concepts (like fears and anxieties) that threaten to overpower us.
Contrast: The poem is rich in contrasts, such as ‘day’ and ‘night’, which serve to explore the varying intensities of our inner fears and anxieties.
Repetition: The repetition of ‘One need not be a Chamber – to be Haunted’ hammer home the poem’s central theme and message.

Keep in mind that Dickinson’s use of these language techniques - from alliteration to contrast - help to consider the psychological aspect of haunting alongside its typical physical connotations. This makes the poem a complex discussion of internal vs. external realities, with bold language choices reflecting the boldness of this exploration.