There is little information on the vocalizations of Dusky Hummingbird. This species has a chattering call that is similar to the homologous vocalization of Broad-billed Hummingbird (Cynanthus latirostris), but is "softer and more liquid or spluttering" (Howell and Webb 1995). Dusky Hummingbird also has "dry, slightly buzzy chips and a quiet, dry, chippering warble (song?)" (Howell and Webb 1995).
There are few known audio recordings of vocalizations of Dusky Hummingbird; additional audio recordings can be heard at xeno-canto.