The song of the Resplendent Quetzal is a series of "deep, smooth, slurred notes in simple patterns: keow kowee keow k'loo keow k'loo keeloo ... often strikingly melodious" (Stiles and Skutch 1989). A common vocalization, often given in flight or when agitated, is "a sharp, cackling perwicka" (Stiles and Skutch 1989). A similar vocalization, wac-wac or very-good very-good, is given by the male in a display flight (Skutch 1944, Stiles and Skutch 1989).
Skutch (1944) described five varied vocalizations of the Resplendent Quetzal. In Guatemala, LaBastille et al. (1972) also heard the five primary vocalizations noted by Skutch, as well as three additional vocalizations. They described two vocalizations as unique to the male: 1) morning high-pitched, two-note whistle; and 2) gee-gee high-pitched call. They also described the vocalizations shared by both sexes: 1) wahc-ah-wahc (Skutch's wac-wac) identification call; 2) wec-wec agitation call with accompanying flick of tail; 3) coouee ascending whistle from high in trees or nest hole; 4) uwac ascending call during courtship chase; 5) guttural chatter from tree tops when disturbed; 6) nasal whining buzzing of begging chicks.