Both male and female mockingbirds sing. They often mimic the sounds of birds (and frogs) around them, including shrikes, blackbirds, orioles, killdeer, jays, hawks, and many others. They go on learning new sounds throughout their lives. The song is a long series of phrases, with each phrase repeated 2-6 times before shifting to a new sound; the songs can go on for 20 seconds or more. Many of the phrases are whistled, but mockingbirds also make sharp rasps, scolds, and trills. Unmated males are the most insistent singers, carrying on late all day and late into the night. Brown Thrashers have a similar song, but the phrases are less varied and most are delivered just 2-3 times. Gray Catbirds can also sound similar, but their phrases are more nasal, hurried, and slurred.
Northern Mockingbirds make a harsh, dry chew or hew when mobbing nest predators or chasing other mockingbirds. Mates exchange a softer version of this call during incubation and nestling periods, or when the female leaves the nest while incubating. Mockingbirds also make a series of 2-8 short, scratchy chat calls to warn off intruders. Females make a single chat when disturbed.