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.

The Tyranni (suboscines) are a suborder of passerine birds that includes more than 1,000 species, the large majority of which are South American. It is named after the type genus Tyrannus. These have a different anatomy of the syrinx musculature than the oscines, hence the common name of suboscines.