The syrinx is the vocal organ that songbirds use to produce complex songs.
Unlike the human larynx, the syrinx sits where the windpipe divides into the two bronchi, near the base of a bird’s trachea. Muscles can control each side separately, allowing some birds to produce two notes at once or create rapidly changing harmonies.
The syrinx is especially developed in oscine songbirds, including nightingales, canaries, and mockingbirds. Its structure helps explain why birds can make sounds that seem far richer than their small bodies suggest.
A common mix-up is calling the syrinx a bird’s “voice box.” That comparison is useful, but birds do not have a mammalian-style larynx performing the same sound-producing role. The beak, tongue, throat, and resonating body cavities then shape the sound produced by the syrinx.