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A siren is a loud noise maker. The original version would yield sounds under water, suggesting a link with the sirens of Greek mythology. Most modern ones are civil defense or "air raid" sirens, tornado sirens, or the sirens on emergency service vehicles such as ambulances, police cars and fire trucks. There are two general types, pneumatic and electronic. The device was invented by the Scottish natural philosopher (physicist) John Robison. It was improved and given its name by Charles Cagniard de la Tour. Image File history File links Please see the file description page for further information. ...
It has been suggested that this article or section be merged with Siren (noisemaker). ...
There are a few possible meanings for Siren: Siren, the mythological creature Siren (amphibian), a type of salamander Sirenia, an order of aquatic mammals including the dugong and the manatee Siren (noisemaker), devices to sound an alarm or used as a musical instrument Siren, Wisconsin, a village in the United...
Image File history File links Size of this preview: 651 × 600 pixel Image in higher resolution (1846 × 1700 pixel, file size: 1. ...
Image File history File links Size of this preview: 651 × 600 pixel Image in higher resolution (1846 × 1700 pixel, file size: 1. ...
In Greek mythology, the Sirens or Seirenes (Greek Σειρῆνας) were sea nymphs who lived on an island called Sirenum scopuli which was surrounded by cliffs and rocks. ...
American Signal AL-8000 in OFallon, Illinois A civil defense siren (also referred to as an air raid siren, tornado siren, or outdoor warning siren) is an electrically-powered mechanical device for generating sound to provide warning of approaching danger and to indicate when the danger has passed. ...
Emergency services are public services that deal with emergencies and other aspects of Public Safety. ...
An ambulance in San Jose Del Cabo, Mexico A Helicopter used as an Ambulance. ...
Ford Crown Victoria Police Interceptor of the United States Federal Protective Service. ...
A fire apparatus, fire engine or fire truck or fire appliance usually refers to a vehicle designed to fight fires. ...
Motto: (Latin) No one provokes me with impunity(English) Wha daur meddle wi me? (Scots)[1] Anthem: Multiple unofficial anthems Capital Edinburgh Largest city Glasgow Official languages English, Gaelic, Scots[2] Government - Queen Queen Elizabeth II - Prime Minister Tony Blair MP - First Minister Jack McConnell MSP Unification - by Kenneth I...
John Robison (February 4, 1739 - January 30, 1805) was a Scottish physicist and inventor. ...
Charles Cagniard de la Tour (March 31, 1777 - July 5, 1859), French engineer and physicist, was born in Paris, and after attending the École Polytechnique became one of the ingenieurs geographiques. ...
Pneumatic
 An electromechanical siren (a German E57) 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). As the holes in the rotating disk alternately prevent and allow air to flow it results in alternating compressed and rarefied air pressure, i.e. sound. Such sirens can consume large amounts of energy. Image File history File links pneumatic Siren by Thomas Schulze (12. ...
Image File history File links pneumatic Siren by Thomas Schulze (12. ...
An aerophone is any musical instrument which produces sound primarily by causing a body of air to vibrate, without the use of strings or membranes, and without the vibration of the instrument itself adding considerably to the sound. ...
A siren disk is a disk with holes variously spaced, such that when spun in front of an air jet, the holes modulate the jet in a primarily binary (on/off) fashion, to directly produce sound. ...
Sound is a disturbance of mechanical energy that propagates through matter as a longitudinal wave, and therefore is a mechanical wave. ...
In United States English language usage, vehicular pneumatic sirens are sometimes referred to as mechanical or coaster sirens, to differentiate them from devices which make noise electronically. One example is the Q2B electromechanical siren sold by Federal Signal Corporation. Because of high amp draw (280 amps when power is applied) its application is normally limited to fire apparatus, though it has seen increasing use on type IV ambulances and rescue-squad vehicles. Its distinct tone of urgency, sound power (123 dB at 10 feet) and square sound waves help account for its effectiveness. The English language is a West Germanic language that originates in England. ...
Firefighter with an axe A firefighter, sometimes still called a fireman though women have increasingly joined firefighting units, is a person who is trained and equipped to put out fires, rescue people and in some areas provide emergency medical services. ...
An ambulance in San Jose Del Cabo, Mexico A Helicopter used as an Ambulance. ...
Electronic Electronic sirens incorporate circuits such as oscillators, modulators, and amplifiers to synthesize a selected siren tone (wail, yelp, pierce/priority/phaser, hi-lo, scan, airhorn and a few more) which is played through external speakers. It is not unusual, especially in the case of modern fire engines, to see an emergency vehicle equipped with both types of sirens. Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ...
In telecommunications, modulation is the process of varying a periodic waveform, i. ...
Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ...
As art Sirens are also used as musical instruments, such as in Edgard Varèse's Hyperprism (1924), George Antheil's "Ballet Mécanique" (1926), 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. A musical instrument is a device constructed or modified with the purpose of making music. ...
Edgard Victor Achille Charles Varèse (December 22, 1883 – November 6, 1965) was a French-born composer. ...
George Antheil (June 8, 1900 – February 12, 1959) was an American composer and pianist of German and Lutheran descent, born in Trenton, New Jersey. ...
Ballet mécanique is a 1924 experimental film directed by Fernand Léger and Dudley Murphy with music by George Antheil and starring Alice Prin. ...
1929 (MCMXXIX) was a common year starting on Tuesday (link will take you to calendar). ...
Henry Fillmore (3 December 1881 - 7 December 1956) was a United States composer and publisher. ...
Evelyn Glennie on the cover of her greatest hits album. ...
Vehicle-mounted
Approvals or certifications Most governments have standards for vehicle-mounted sirens. For example, in California, sirens are designated Class A or Class B. In non-technical terms, a Class A siren is so loud it can be mounted nearly anywhere on a vehicle. 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.
Sirens must also be approved by local agencies, in some cases. For example, the California Highway Patrol approves specific models for use on every emergency vehicle in the state. The approval is important because it ensures the devices perform adequately. Moreover, using unapproved devices could be a factor in determining fault if a collision occurs. (CHP) is a state agency that acts as the state police force of California. ...
Best practices The worst installations are those where the siren sound is emitted above and slightly behind the vehicle occupants such as cases where a light-bar mounted speaker is used on a sedan or pickup. Vehicles with concealed sirens also tend to have high noise levels inside. In some cases, concealed or poor installations produce noise levels which can cause permanent hearing damage to vehicle occupants.
Siren speakers, or mechanical sirens, should always be mounted ahead of the passenger compartment. This reduces the noise for occupants and makes two-way radio and mobile telephone audio more intelligible during siren use. It also puts the sound where it will serve a useful purpose. Studies in some agencies operating emergency vehicles show sound pressure levels over 120dba in the passenger compartment. In one study, a specific vehicle's engine sounds and the siren produced sound levels over 123dba in the passenger compartment.
Electric-motor-driven mechanical sirens may draw 50 to 200 amperes at 12VDC when spinning up to operating speed. Appropriate wiring and transient protection for modern engine control computers is a necessary part of an installation. Wiring should be similar in size to the wiring to the vehicle engine starter motor. Mechanical vehicle mounted devices usually have an electric brake, a solenoid that presses a pad of friction material against the siren rotor. When an emergency vehicle arrives on-scene or is cancelled en route, the vehicle operator can rapidly stop the siren.
Multi-speaker electronic sirens often are alleged to have dead spots at certain angles to the vehicle's direction of travel. These are caused by phase differences in speaker wiring. The sound coming from the speaker array can phase-cancel in some situations. A crude, static test for dead spots is to apply white noise from an unsquelched F.M. two-way radio to the siren amplifier's auxiliary input then walk around the vehicle making sure the sound doesn't have any unexpected nulls.
See also American Signal AL-8000 in OFallon, Illinois A civil defense siren (also referred to as an air raid siren, tornado siren, or outdoor warning siren) is an electrically-powered mechanical device for generating sound to provide warning of approaching danger and to indicate when the danger has passed. ...
Thunderbolt Model 1003 The Thunderbolt siren was an electro-mechanical warning siren once manufactured in the United States by Federal Signal Corporation. ...
Audio sample: Klaxon ( file info) — A sample of a submarine dive klaxon used by United States Navy submarines during World War II Problems listening to the file? See media help. ...
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