Syrinx

The syrinx is the vocal organ of birds, located where the trachea divides into the bronchi. Its vibrating tissues can produce complex sounds, often with independent control of the two sides.

Labia (bird vocal organ): The paired vibrating tissue structures in the syrinx that generate sound as air passes through them. Their vibration is the immediate source of sound in many bird syringes.
Trachea: A tube that conducts air between the larynx and the bronchi in many vertebrates. The trachea ends at the branching point where the syrinx is located.
Bird vocalization: Sound production by birds, including calls and songs used in communication and other behaviors. The syrinx is the principal organ that produces bird vocalizations.
Larynx: An organ in the airway that produces sound and helps protect the lower respiratory tract in many vertebrates. Birds produce vocal sounds mainly in the syrinx rather than the larynx.
Air sac: A thin-walled extension of a bird's respiratory system that helps move air through the lungs. Air sacs sustain airflow through the syrinx during vocalization.
Bird respiratory system: A respiratory system with rigid lungs and air sacs that moves air in a largely one-way flow through the lungs. The syrinx works within this distinctive airflow system.
Birdsong learning: The process by which some birds acquire songs through experience, often by copying adult models. Learned song depends on coordinated control of syringeal sound production.
Mammalian vocal folds: Paired tissue folds in the larynx that vibrate to produce most mammalian voiced sounds. They are the mammalian counterpart to syringeal sound-producing tissues.
Bronchus: A major airway branching from the trachea and carrying air into a lung. The syrinx sits at the tracheal junction with the two bronchi.
Lung: An organ that exchanges oxygen and carbon dioxide between air and blood. Air passing through the lungs also supplies airflow for syringeal sound.

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