What is the effect of the alliteration "Smallest space a sheet...on a ...shelf" in the poem "Small Town Dance" by Judith Wright?

of the initial
"s" sound is also known as sibiliance, but the alliteration in this poem that you have
identified also includes repetition of the "sh" sound in "sheet" and
"shelf," which crams a lot of alliteration in to these two lines:

That white Expanse
reduces to a neat
compression
sitting in the smallest space
a sheet can pack in on a cupboard shelf.

It is important to remember the context of...