The song of Montezuma Oropendola is a loud gurgle, which is audible for up to 150 m (Jaramillo and Burke 1999). Skutch (1954) described it as "a long-drawn, far-carrying liquid gurgle, an undulatory sound ascending in pitch. When heard in the distance it is most melodious, but when the performer is nearby his screeching overtones somewhat mar the effect". Jaramillo and Burke (1999) note that the song consists of two parts: "The first part of the song is a series of bubby, conversational, tinkling notes overlaid by metallic sounds that ascend the scale as they increase in volume. The second part is a loud, descending, liquid gurgle ... The complete song, which lasts under 3 seconds, can be interpreted as tic-tic-glic-glac ...gluuuuuuluuuuu or ticki-ticki-ticki-ticki-ticki-WHAAAoooo". This song is accompanied by the bow display. In common with Olive Oropendola (P. bifasciatus), the songs of Montezuma Oropendola include both very long notes, and high levels of note overlap (the production of two sounds at the same time). This may indicate "that these males are performing near the upper limits of their [physiological] abilities" (Price and Lanyon 2004).
Calls of Montezuma Oropendola include "a whining waaaah" (Jaramillo and Burke 1999); an alarm call given by the male, "a harsh, stentorian cack" (Skutch 1954, Jaramillo and Burke 1999); and "a full, throaty cluck" given by the female (Skutch 1954, Jaramillo and Burke 1999).