Oxymoron
The pairing, within one phrase, of two contradictory terms: a deafening silence, sweet sorrow.
An oxymoron juxtaposes two logically incompatible terms within one expression: "a deafening silence," "living dead," "bittersweet." The contradiction is not clumsiness but new meaning: the oxymoron names complex realities ordinary vocabulary cannot capture.
It is the figure of ambivalent states — grief mixed with relief, love mixed with dread — which is why poetry and intimate narrative use it so much. Used sparingly, it crystallizes a tension in two words; overused, it produces the opposite effect, a mannerism that signals the effect instead of producing it.
Example
"Parting is such sweet sorrow"