Syrinx

The thrush's song flows from the syrinx buried deep in his chest. Here membranes vibrate and squeeze the air that rushes out of the lungs. These membranes circle the confluence of the bronchi, turning a toneless exhalation into sweet music that ascends the trachea and flows out of the mouth. Only birds make sound this way, using a biological hybrid between the flute's swirling tube of air and the oboe's vibrating membranes. Birds change the texture and tone of their song by adjusting tension in the muscles that wrap the syrinx; the thrush's song is sculpted by at least ten muscles in the syrinx, each one shorter than a grain of rice.

-- David George Haskell