The antbirds are a large passerine bird family, Thamnophilidae, found across subtropical and tropical Central and South America, from Mexico to Argentina. There are more than 230 species, known variously as antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds. They are related to the antthrushes and antpittas, the tapaculos, the gnateaters and the ovenbirds. Despite some species' common names, this family is not closely related to the wrens, vireos or shrikes.

The syrinx is the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal folds of mammals. The sound is produced by vibrations of some or all of the membrana tympaniformis and the pessulus, caused by air flowing through the syrinx. This sets up a self-oscillating system that modulates the airflow creating the sound. The muscles modulate the sound shape by changing the tension of the membranes and the bronchial openings. The syrinx enables some species of birds to mimic human speech.