Syrinx (bird anatomy)

Syrinx (Greek σύριγξ for pan pipes) is the name for the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal cords of mammals. The sound is produced by vibrations of some or all of the membrana tympaniformis (the walls of the syrinx) and the pessulus caused by air flowing through the syrinx. This sets up a self-oscillating system which 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 (such as parrots, crows, and mynas) to mimic human speech. Unlike the larynx of mammals, the syrinx is located where the trachea forks into the lungs. Thus, lateralization of bird song is possible and some songbirds can produce more than one sound at a time. Some species of birds, such as New World vultures, lack a syrinx and communicate through throaty hisses.