First, let's discuss rhythm.

In stanzas 1 and 2, almost every line has 10 syllables, providing a steady rhythm.  In the last stanza, the lines are shorter, mostly 8 syllables a piece.  This gives a sort of "drive" to the conclusion.  The poet adds further force to the ending by repeating the phrase, "What did I know, what did I know."

Like most poets, Hayden uses alliteration, that is, he uses words that have the same initial consonant sound.  For example:

a) weekday weather

b) banked fires blaze

c) love's austere and lonely offices

Hayden also uses a number of words that make us think of sounds: cracked, splintering, call, speaking.