Whistle

A whistle is a one-note woodwind instrument which produces sound from a stream of forced air. (For the sound produced with the mouth, see whistling and whistled language.)

Many types exist, from small police and sports whistles (also called pea whistles), to much larger steam whistles used on locomotives and ships. They are not usually considered 'musical' as such, but musical versions that work on the same principle exist, including any of several 2-octave musical instruments known as tin whistles (sometimes known as pennywhistles or low whistles), organ pipes and the recorder. Pea whistles are used in jazz and Latin music as a percussion instrument.

The whistle works by causing the smooth flow of air to be split by a narrow blade, sometimes called a fipple, creating a turbulent vortex which causes the air to vibrate. By attaching a resonant chamber to the basic whistle, it may be tuned to a particular note and made louder. The length of the chamber typically defines the resonant frequency. A whistle may also contain a small light ball, usually called the pea, which rattles around inside, creating a chaotic vibrato effect that intensifies the sound. Japanese bird whistles use several small balls and are half filled with water in order to reproduce the sound of a bird song.

A steam whistle works the same way, but using steam as a source of pressure: such whistles can produce extremely high sound intensities.

Sometimes, unintentional whistles can be set up. A common one is the opened sunroof of a car: air passing over the top of the vehicle can, at certain speeds, strike the back edge of the sunroof, creating a very low frequency whistle which is resonated by the closed interior of the car. Since the sound frequency is infrasonic, around 4 Hz, the effect is very uncomfortable for occupants, who feel the vibration rather than hear it. Such low frequencies can induce nausea, headache, disorientation and dizziness. The effect can be prevented by opening a side window a few inches. Subsonic whistles have also been developed for use as weapons, or to deliberately create a sense of uneasiness in an enemy.

"the whitles go WOOOO!!!!".... ~BUBB RUBB~