(noun) The vocal organ of birds. Birds have no vocal cords, and the syrinx is the avian equivalent of the larynx of mammals. The syrinx is located at the base of the trachea where it splits into two branches for the lungs, and up to 12 different muscles control the syrinx to change membrane tension and vibrate the walls in order to produce sounds of different tones and pitches. The word "syrinx" is derived from a Greek word for tube, and is also related a name for a specific type of pan pipes.
What makes the syrinx remarkable is that birds have the ability to control the left and right sides of the organ independently, creating more intricate vocalizations either simultaneously or in a rapid progression for more complex songs and calls. The complexity of the syrinx varies among different bird species, and is most complex in passerines that have a greater repertoire of vocalizations. Birds with longer windpipes, such as swans, geese and cranes, are able to make deeper tones, while smaller birds are limited to higher pitches but also have greater overall complexity in their full songs. Unlike mammals that only use a fraction of air to create sound, birds use very close to 100 percent of the air they intake to make song.
Photo – Black and White Warbler © Nick Saunders
SIH-reeenks or SREEENKS
Song Box, Syringes (plural)