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1. a device for making a shrill high-pitched sound by means of air or steam under pressure
2. Music any pipe that is blown down its end and produces sounds on the principle of a flue pipe, usually having as a mouthpiece a fipple cut in the side



a generator that converts the energy of a fluid stream into the energy of acoustic vibrations. Unlike a siren, a whistle has no moving parts and is therefore simpler to manufacture and use. Depending on the working fluid for which they are designed, whistles are classified as gas-jet or jet liquid. Gas-jet whistles in turn are subdivided into low- and high-pressure types. As a rule, low-pressure whistles have a relatively high efficiency but generate little power, and until recently they were used only for signaling. However, with methods for increasing power output, uses have now been found for whistles in industry, for example, in the coagulation of aerosols and in the acceleration of processes of heat and mass transfer.

The simplest low-pressure whistle is the familiar lip whistle, which consists of a slotted inlet and a resonance chamber, usually cylindrical in shape. Air fed into the inlet is split into two streams by the sharp edge of the resonator. One stream exits into the surrounding medium, while the other enters the resonance chamber, thereby increasing the pressure. After a period of time that depends on the size of the chamber, the second stream interrupts the main flow, as a result of which there is a periodic compression and rarefaction of the air that is propagated as acoustic waves. Lip whistles ordinarily operate at air pressures not exceeding 1.4 atmospheres and generate acoustic power of the order of 1 watt. Some designs enable several kilowatts of power to be generated.

The ultrasonic Galton whistle and vortex whistles are further examples of low-pressure devices. Vortex whistles have a cylindrical chamber into which a gas or liquid is introduced tangentially. A narrow tube extends along the axis of the chamber, and it is through this tube that the gas exits, radiating sound energy. Elastic vibrations are induced by a combination of the pressure decrease along the whistle axis that results from vortex motion and the periodic pressure equalization that results from the rush of gas from the atmosphere into the tube’s outlet. At frequencies up to 30 kilohertz, the power output of a vortex whistle is usually of the order of several watts. A representative high-pressure whistle is the Hartmann generator, which has a maximum power output of 0.5 kilowatt.

The design and operating principles of jet liquid whistles are analogous to those of the gas-jet type. The most common are lamellar jet liquid whistles, which function by using a liquid stream under high pressure to excite resonant vibrations of the vibrator—a blade or rod.


Shkol’nikova, P. Sh. “Vozdukhostruinye generatory akusticheskikh kolebanii dlia koaguliatsii aerozolei.” Akusticheskii zhurnal, 1963, vol. 9, no. 3, pp. 368–75.
Bergmann, L. Ul’trazvuk i ego primenenie v nauke i tekhnike, 2nd ed. Moscow, 1957. (Translated from German.)


References in periodicals archive ?
When his Royal Highness came into our showroom, I showed him a labrador whistle and said 'This wouldn't do for your spaniels'.
ACME has made over a billion whistles in its 150-year history, and traditionally stamped them with its marque.
I infer rough behaviour at the Gnoll School in those wartime days and the need for shrill whistles whether from the police, the railway guards or from the schoolteachers because I can confirm that my parents entrusted my younger sister to the safer haven of St David's Church Primary School about half a mile away.
They responded with the hashtag #ElPitoDeMancera, a double entendre referring to Mancera's whistle plan and, well, his manhood, (http://www.
Ian Haney Lopez, Dog Whistle Politics: How Coded Racial Appeals Have Reinvented Racism & Wrecked the Middle Class, New York, Oxford University Press, 2014, 304pp; 11.
Whistles are louder, and their pitch is clearer than spoken calls for assistance.
Higher pitched whistles tend to carry over longer distances, so keep that in mind.
Instead, Herzing and her team invented a series of whistles and ascribed them to certain things - one of which was sargassum - and trained the dolphins to repeat the whistles when they encountered those things.
Through whistles the workers would inform the citizens that they could put the waste at the points fixed for picking waste, sources said.
We put the whistle in the exhaust and gave several long blasts and then pulled it out and threw it in the trunk.
To interrogate kettle whistles, Henrywood, working with his academic supervisor, Anurag Agarwal, tested a series of simplified kettle whistles in an apparatus by forcing air through them at various speeds.
As seen in the video embedded in the whistled website, it is very simple to set up and will detect all the very different types of whistles.