Luc Sante at the NYRB:
Ashbery’s was marked above all by a calm, discursive voice, going along at a walking pace, often seeming to have been caught in midstream, maybe half-heard from outside through the curtains. That voice could occasionally sound explicitly poetic or expressionistically fractured, but more often—and more consistently as time went by—it sounded conversational, demotic, mild, even-toned, deep-dish American. Its apparent placidity allowed for all sorts of things to appear bobbing happily in its current: recondite allusions, philosophical asides, foreign idioms, schoolyard jokes, forgotten cultural detritus of all sorts, even the occasional narrative or analysis or argument.
Much of his work gives the impression of having been piped straight to the surface from his unconscious, although it certainly passed through a powerful poetic engine that determined line breaks and measured flow and regulated music. His reading voice maintained that imperturbable meandering pace, never succumbing to declamation or melodrama or the pregnant pauses of needier poets but issuing a steady stream of words in unexpected patterns, so that young poets would attend his readings not just to hear him but to furtively scribble the images and lines his had touched off in their own fugue states.