AY Honors/Whistles/Answer Key

2006-01-09T02:50:47Z

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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 [[train whistle]]s, which are [[steam whistle]]s specifically designed for use on [[locomotive]]s and [[ship]]s. Although whistles have a musical characteristic (for example train whistles sound a minor-seventh musical chord) whistles are not usually considered 'musical' in the sense of being able to play a chosen melody. However, musical whistles exist, including any of several 2-[[octave]] musical instruments known as [[tin whistle]]s (sometimes known as pennywhistles or low whistles), as well as the [[calliope]] (an array of separately actuable steam whistles), [[Organ (music)|organ]] pipes and the [[recorder]]. Pea whistles are used in [[jazz]] and [[Latin music]] as a [[Percussion_instrument|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 [[turbulence|turbulent]] [[vortex]] which causes the air to vibrate. By attaching a [[resonance|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 [[chaos|chaotic]] [[vibrato]] effect that intensifies the sound. [[Japanese people|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 [[Automobile|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 [[Hertz|Hz]], the effect is very uncomfortable for occupants, who feel the vibration rather than hear it. Such low frequencies can induce [[nausea]], [[headache]], [[delirium|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.

==Industrial whistles==
[[Image:Police whistles.jpg|left|250 px|Examples of police whistles]]

Industrial whistles are used for [[signal]]ling and [[time|timekeeping]] both on [[railroad]] and [[ship]]s, and in [[factory|factories]]. Most of these whistles were [[steam power]]ed and not standardized. Individual [[locomotive]]s could be identified by their whistles. At noontime in industrial areas up into the [[1950s]] whistles of every pitch could be heard, as each factory had a boiler and a whistle, if not full steam power.

Railroads in particular used elaborate whistle codes for communication both within the [[train]] and with other trains. These methods are maintained today with motor-powered [[air horn]]s. Trucks also use air horns, especially since they often have air brakes and so there is already a source of compressed air on board.

[[Train whistle]]s generally produce three or four different frequencies at the same time, to produce a non-[[major chord]], that is distinct, loud, and low in pitch.

Whistles are often used as warning devices or as safety devices serving to attract attention to the user. Some [[cyclist]]s use a whistle as a substitute for a [[bell (instrument) | bell]] or [[Horn (acoustic)|horn]]. It should be noted, however, that many jurisdictions require that the warning device be permanently attached to the [[bicycle]].

[[Category:Flutes]]

[[es:Silbato]]
[[ja:ホイッスル]]
[[nl:Fluitje]]
[[pl:Gwizdek]]

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AY Honors/Whistles/Answer Key