The song of Blue-black Grosbeak is described as "ca. 6 successively lower, clear, mellow whistles, usually ending with a sharp little warble" (Stiles and Skutch 1989) and as "a rich, slightly sad, slurred, descending warble often fading into a soft, squeaky ending" (Howell and Webb 1995). Blue-black Grosbeak sings from concealed sites with dense understory (Hilty 2003). Both sexes sing (Skutch 1954). Blue-black Grosbeak also has a "sweet, prolonged flight song [that] is rarely heard (Stiles and Skutch 1989; see also Skutch 1954).
The most frequent call of Blue-black Grosbeak is described as "a sharp, hard spek or chik" (Stiles and Skutch 1989) or as "a sharp, nasal to slightly squeaky plik or chik, and pli-dik or ch-dik" (Howell and Webb 1995); also gives low, nasal notes (Stiles and Skutch 1989).