The song of the Green Violetear is highly variable between individuals (Barrantes et al. 2008), although songs tend to be more similar among groups of neighboring males than they are to songs of more distant males (Gaunt et al. 1994). The song is described as "a rhythmic, jerky, metallic chipping, t'issik-t'issik, t'issik-t'issik ... punctuated irregularly with tik and tssi notes, or ch-it chi-i-it chi-chi-it chi-it chi-i-it ..., often prolonged" (Howell and Webb 1995); "a vigorous but unmelodious 2- to 4-note phrase - CHEEP chut-chut, chip CHEEP chut, or CHEET-chup - repeated rapidly for minutes on end" (Stiles and Skutch 1989); and as a loud two-noted tsip-chup or tsup-chip (Hilty and Brown 1986).
The song is ventriloquial, and is given from a high perch, such as a bare twig (Hilty and Brown 1986, Stiles and Skutch 1989). Males often sing solitarily or in small leks, and they call continuously throughout the year except during the molt in April and on days of disagreeable weather (Wagner 1945).
Other vocalizations include "a hard, dry rattle, often given when feeding" (Howell and Webb 1995); and "a sharp, dry, rather low-pitched chut or zut" (Stiles and Skutch 1989).