The territorial song (or "A-song") of Puerto Rican Screech-Owl is "a short, relatively deep, somewhat guttural, toad-like quavering trill of c. 3-5 seconds' duration, rrurrrrrrr" (König and Weick 2008).
For a representative audio recording with sonogram, see audio
The "B-song" is used in duets between male and female (König and Weick 2008), and perhaps in other contexts (aggression?).
Other vocalizations of Puerto Rican Screech-Owl include "a soft cackling gu-gu", which may be a contact call (König and Weick 2008), and "a loud coo-coo" (König and Weick 2008). The latter call gave rise to the local English name, "Cuckoo Bird".