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| | Siren (noisemaker) - Wikipedia, the free encyclopedia (via CobWeb/3.1 planetlab2.cs.umd.edu) (Site not responding. Last check: 2007-10-08) |
 | | The pneumatic siren, which is a free aerophone, consists of a rotating disk with holes in it (called a siren disk or rotor), such that the material between the holes interrupt a flow air from fixed holes on the outside of the unit (called a stator). |
 | | Sirens are also used as musical instruments, such as in Edgard Varèse's Hyperprism (1924), The Klaxon: March of the Automobiles (1929 by Henry Fillmore, Ionisation (1931), recorded, in his Poeme Electronique (1958) and, (in a CBS News 60 Minutes segment) by experimental percussionist Evelyn Glennie. |
 | | Class B sirens are not as loud and must be mounted on a plane parallel to the level roadway and parallel to the direction the vehicle travels when driving in a straight line. |
| en.wikipedia.org.cob-web.org:8888 /wiki/Siren_(noisemaker) (824 words) |
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