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In a pneumatic siren, the stator is the part which cuts off and reopens air as rotating blades of a chopper move past the port holes of the stator, generating sound. The pitch of the siren's sound is a function of the speed of the rotor and the number of holes in the stator. A siren with only one row of ports is called a single tone siren.
A siren was used in Bob Dylan's classic album, Highway 61 Revisited. One is also heard in Stevie Wonder's song "Sir Duke" just before the second chorus. Dan Zanes also uses a siren in his version of "Washington at Valley Forge." Acme is the trade name of J Hudson & Co of Birmingham, England, who developed and patented the Acme siren in 1895. It ...
Federal Signal Model 5 in Ballston Spa, New York, U.S.. Sirens are sometimes integrated into a warning system that links sirens with other warning media, such as the radio and TV Emergency Alert System, NOAA Weather Radio, telephone alerting systems, Reverse 911, Cable Override, and wireless alerting systems in the United States and the National Public Alerting System, Alert Ready, in Canada.
The use of flashing lights and sirens is colloquially known as blues and twos, which refers to the blue lights and the two-tone siren once commonplace (although most sirens now use a range of tones). In the UK, only blue lights are used to denote emergency vehicles (although other colours may be used as sidelights, stop indicators, etc.).
Rumbler siren. A Rumbler siren is a type of emergency vehicle siren used primarily in the United States.Developed in 2007 by Federal Signal Corporation, and sounding at a low-frequency level, it is designed to be heard by motorists who may otherwise be unable to hear high-frequency sirens due to ambient noise, such as urban traffic.
The Modulators in Chicago's siren system formerly used to run on the Alternate Wail tone during tornado warnings in order to vary from emergency vehicle sirens. However, in O'Hare International Airport, instead of using the main UV Wail or Attack, they use an Eclipse 8 (possibly) sound card doing attack. Before that is the Westminster Chimes ...
As far back as Ancient Greece, sound effects have been used in entertainment productions. Sound effects (also known as sound FX, SFX, or simply FX) are used to enhance theatre, radio, film, television, video games, and online media. Sound effects were originally added to productions by creating the sounds needed in real-time.
A long-range acoustic device (LRAD), acoustic hailing device (AHD) or sound cannon is a specialized loudspeaker that produces sound at high power for communicating at a distance. It has been used as a method of crowd control , which has caused permanent hearing damage , having an extremely high decibel capacity (up to 160 dB measured at one ...