Air horn

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Steam whistle from a supertanker, in Merseyside Maritime Museum, United Kingdom Supertanker Steam whistle, Merseyside Maritime Museum.jpg
Steam whistle from a supertanker, in Merseyside Maritime Museum, United Kingdom

An air horn is a pneumatic device designed to create an extremely loud noise for signaling purposes. It usually consists of a source which produces compressed air, which passes into a horn through a reed or diaphragm. The stream of air causes the reed or diaphragm to vibrate, creating sound waves, then the horn amplifies the sound making it louder. Air horns are widely employed as vehicle horns, installed on large buses, semi-trailer trucks, fire trucks, trains, and some ambulances as a warning device, and on ships as a signaling device.

Contents

Operation

Diagram of a typical locomotive air horn power chamber, showing operation Powerchamber.JPG
Diagram of a typical locomotive air horn power chamber, showing operation

An air horn consists of a flaring metal or plastic horn or trumpet (called the "bell") attached to a small air chamber containing a metal reed or diaphragm in the throat of the horn. Compressed air flows from an inlet line through a narrow opening past the reed or diaphragm, causing it to vibrate, which creates sound waves. The flaring horn serves as an acoustic impedance transformer to improve the transfer of sound energy from the diaphragm to the open air, making the sound louder. In most horns it also determines the pitch of the sound. When vibrated by the diaphragm, the column of air in the horn vibrates in standing waves. The length of the horn determines the wavelength of the sound waves generated, and thus the fundamental frequency (pitch) of the note produced by the horn. The longer the horn, the lower the pitch.

Larger air horns used on ships and foghorns function similarly to a whistle; instead of a diaphragm the air escapes from a closed cylindrical resonator chamber through a precisely shaped slit directed against a knife edge (fipple). The air blowing past the knife edge oscillates, creating sound waves. The oscillations excite standing waves in the resonator chamber, so the length of the chamber determines the pitch of the note produced.

Trucks and buses

In trucks and buses, the air horn is powered with compressed air from the vehicle's air brake system. In trucks, a cord mounted on the ceiling of the operator's cab is pulled or in buses, a valve lever on the side of the dashboard is pushed down or pulled up to open the valve, supplying varying amounts of air to the horn. Thus, an outstretched hand reaching upward and pumping is a signal to the driver of an air horn equipped vehicle, requesting a toot. In modern trucks and buses, the horn is actuated by a button on the steering wheel (just like a normal car horn). Some trucks and buses have both electric and air horn, selectable by a switch on the dashboard. This is to prevent the use of the powerful air horn in populated areas.

Emergency vehicles

Toronto Fire uses air horn while responding

Many fire trucks, ambulances, and other large emergency vehicles operate air horns as a means of warning vehicles to clear the right-of-way.

There are also electronic horns for emergency vehicles, which produce a similar easily recognizable sound. These are typically integrated into the same system as the vehicle's electronic siren, and sound through the same speakers. In the last several decades, electronic sound systems with more widely varying frequencies have been chosen as common supplemental warning systems.

Locomotives

Leslie model S5T five-chime locomotive air horn. LeslieS5T.jpg
Leslie model S5T five-chime locomotive air horn.

Originally, diesel locomotives were equipped with truck horns. After an accident in which a driver mistook a train for a truck, the need for a unique-sounding train horn became clear. [1] Consequently, North American trains now have at least two horns with different tones forming the airhorn, that sound simultaneously,[ citation needed ] creating a harmonic interval or chord. Each individual horn is called a "chime". Three and five-chime configurations are the most common, but two chime horns also exist. [2]

Fifteen to twenty seconds before entering a level crossing, federal law requires locomotives to sound their horns in a standard warning sequence. This succession consists of two long, one short, and one long horn sounding repeated as necessary until the locomotive clears the crossing. Exceptions to federal law occur in locations with established quiet zone ordinances that prohibit sounding locomotive horns.

In recent years, it has become a fad for bicycle, car, and truck enthusiasts to install large air horns on their vehicles. [3] Some jurisdictions do not allow an airhorn to be attached, whether or not it can be activated.[ citation needed ]

Cyclist Yannick Read attached a train horn to his bicycle and set the Guinness World Record for the world's loudest bicycle horn. [4]

Portable or personal air horns

A small portable air horn used for sporting events, boating, or safety, powered by a can of compressed gas. It is operated by pressing a button on the top. Italian Gas Horn.JPG
A small portable air horn used for sporting events, boating, or safety, powered by a can of compressed gas. It is operated by pressing a button on the top.

Portable air horns are also readily available packaged with a can of compressed gas as the air source. These are often sounded by fans at sporting events such as American football, basketball, ice hockey, and association football, and at other events such as graduations, and political conventions.

Small versions are sometimes used as bicycle horns, since they yield a louder warning sound than traditional bicycle bells or bulb reed horns.

Another use is as a non-lethal weapon for self-defense, mainly as an auditory distraction to get away from an attacker. For outdoor activities like hiking, hunting, cross-country skiing, canoeing, fishing, an air horn can be handy to frighten away unwanted or aggressive wildlife, signalling for help and to announce one's location.

Additionally, air horns (especially those that contain fluorocarbons) have the potential to be abused as a substitute for recreational drugs since many such refrigerants can be inhaled for a quick and dangerous intoxication. [5] [ citation needed ]

Use in sports

The air horn is used for signaling goals, home runs, touchdowns, and other points in various sports:

NHL arenas normally employ two horns—a high-pitched horn (or a siren, as in the home arenas of the Boston Bruins and Montreal Canadiens) that announces the end of the period (or the start of instant replay reviews), and a much louder horn sounded when the home team scores and/or wins a game. Some MLB and NFL stadiums use horns for similar purposes, such as when a member of the home team hits a home run or touchdown. In many places, air horns are used for signaling the end of the period or quarter on scoreboard systems.

The idea of a goal horn in NHL ice hockey is said to have begun in 1974, when Bill Wirtz, then-owner of the Chicago Blackhawks, liked the sound of the Kahlenberg Q-3 on his yacht so much that he had another Q-3 mounted inside of the team's home arena, Chicago Stadium, to be sounded whenever the Blackhawks scored a goal. [6] Since then, every NHL, AHL (with the exception of the Chicago Wolves, who instead use a siren and fireworks), ECHL, SHL, and CHL team has picked up a horn, including many more leagues.

In mixed martial arts, an air horn is commonly used to signal the end of a round as opposed to the bell used in boxing and professional wrestling. However, CZW, GCW, and other independent wrestling companies allow air horns, while major companies such as WWE and IMPACT Wrestling have banned them.

Use in music

The air horn is a popular sample in reggae music. Jamaican dancehall music was the first musical genre to use the effect, and has been using the airhorn sample for over 26 years, in live shows as well as on mixtape recordings, and in Puerto Rican reggaeton, a reggae hybrid genre since the late '80s and '90s. [7] The sound effect has recently been used in hip hop music as well.

The "Air Horn Orchestra" gathered at the North Carolina Governor's Mansion every Wednesday for 30 weeks from April 13, 2016, until November 2, 2016, to protest the state's Public Facilities Privacy & Security Act, also known then as House Bill 2, and Governor Pat McCrory by making a loud, disruptive noise. [8] [9] [10] [11] The 30th and final performance on November 2 was expected to set the Guinness World Record for the number of simultaneously sounding air horns, having had 342 participants. This was the last performance owing to the gubernatorial election six days later. [12]

See also

Related Research Articles

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A loudspeaker is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A speaker system, also often simply referred to as a speaker or loudspeaker, comprises one or more such speaker drivers, an enclosure, and electrical connections possibly including a crossover network. The speaker driver can be viewed as a linear motor attached to a diaphragm which couples that motor's movement to motion of air, that is, sound. An audio signal, typically from a microphone, recording, or radio broadcast, is amplified electronically to a power level capable of driving that motor in order to reproduce the sound corresponding to the original unamplified electronic signal. This is thus the opposite function to the microphone; indeed the dynamic speaker driver, by far the most common type, is a linear motor in the same basic configuration as the dynamic microphone which uses such a motor in reverse, as a generator.

<span class="mw-page-title-main">Microphone</span> Device that converts sound into an electrical signal

A microphone, colloquially called a mic, or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers and other electronic devices, such as mobile phones, for recording sounds, speech recognition, VoIP, and other purposes, such as ultrasonic sensors or knock sensors.

<span class="mw-page-title-main">Chicago Blackhawks</span> National Hockey League team in Chicago, Illinois

The Chicago Blackhawks are a professional ice hockey team based in Chicago. The Blackhawks compete in the National Hockey League (NHL) as a member of the Central Division in the Western Conference and have won six Stanley Cup championships since their founding in 1926. They are one of the "Original Six" NHL teams, along with the Detroit Red Wings, Montreal Canadiens, Toronto Maple Leafs, Boston Bruins, and New York Rangers. Since 1995, the team has played their home games at the United Center, which they share with the National Basketball Association's Chicago Bulls; both teams previously played at the now-demolished Chicago Stadium.

A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities. The process of converting one form of energy to another is known as transduction.

Rail transport terms are a form of technical terminology applied to railways. Although many terms are uniform across different nations and companies, they are by no means universal, with differences often originating from parallel development of rail transport systems in different parts of the world, and in the national origins of the engineers and managers who built the inaugural rail infrastructure. An example is the term railroad, used in North America, and railway, generally used in English-speaking countries outside North America and by the International Union of Railways. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist.

<span class="mw-page-title-main">Chicago Stadium</span> Former indoor stadium in Chicago, Illinois, United States

The Chicago Stadium was an indoor arena in Chicago that opened in 1929, closed in 1994 and was demolished in 1995. It was the home of the National Hockey League's Chicago Blackhawks and the National Basketball Association's Chicago Bulls. It was used for numerous other sporting events, opening with a championship boxing match in March 1929. The Stadium was built by Paddy Harmon, a promoter, who sank his entire fortune into the project, only to lose control to the Stadium shareholders, and leave his family nearly penniless a year later when he died. After exiting receivership in 1935, the Stadium was owned by the Norris and Wirtz families until its closure in 1994.

<span class="mw-page-title-main">Siren (alarm)</span> Noise-making device

A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. There are two general types: mechanical and electronic.

<span class="mw-page-title-main">Engine braking</span> Retarding forces within an engine used to slow a vehicle

Engine braking occurs when the retarding forces within an internal combustion engine are used to slow down a motor vehicle, as opposed to using additional external braking mechanisms such as friction brakes or magnetic brakes.

In the field of acoustics, a diaphragm is a transducer intended to inter-convert mechanical vibrations to sounds, or vice versa. It is commonly constructed of a thin membrane or sheet of various materials, suspended at its edges. The varying air pressure of sound waves imparts mechanical vibrations to the diaphragm which can then be converted to some other type of signal; examples of this type of diaphragm are found in microphones and the human eardrum. Conversely a diaphragm vibrated by a source of energy beats against the air, creating sound waves. Examples of this type of diaphragm are loudspeaker cones and earphone diaphragms and are found in air horns.

<span class="mw-page-title-main">Foghorn</span> Device using sound to warn shipping in fog

A foghorn or fog signal is a device that uses sound to warn vehicles of navigational hazards such as rocky coastlines, or boats of the presence of other vessels, in foggy conditions. The term is most often used in relation to marine transport. When visual navigation aids such as lighthouses are obscured, foghorns provide an audible warning of rock outcrops, shoals, headlands, or other dangers to shipping.

<span class="mw-page-title-main">Train whistle</span> Audible signaling device on a steam locomotive

A train whistle or air whistle is an audible signaling device on a steam or gas locomotive, used to warn that the train is approaching, and to communicate with rail workers. Modern diesel and electric locomotives primarily use a powerful air horn instead of a whistle as an audible warning device. However, the word whistle continues to be used by railroaders in referring to such signaling practices as "whistling off".

<span class="mw-page-title-main">Steam whistle</span> Audible warning device powered by steam

A steam whistle is a device used to produce sound in the form of a whistle using live steam, which creates, projects, and amplifies its sound by acting as a vibrating system.

<span class="mw-page-title-main">Crystal earpiece</span>

A crystal earpiece is a type of piezoelectric earphone, producing sound by using a piezoelectric crystal, a material that changes its shape when electricity is applied to it. It is usually designed to plug into the ear canal of the user.

An acoustic horn or waveguide is a tapered sound guide designed to provide an acoustic impedance match between a sound source and free air. This has the effect of maximizing the efficiency with which sound waves from the particular source are transferred to the air. Conversely, a horn can be used at the receiving end to optimize the transfer of sound from the air to a receiver.

<span class="mw-page-title-main">Acoustic cleaning</span>

Acoustic cleaning is a maintenance method used in material-handling and storage systems that handle bulk granular or particulate materials, such as grain elevators, to remove the buildup of material on surfaces. An acoustic cleaning apparatus, usually built into the material-handling equipment, works by generating powerful sound waves which shake particulates loose from surfaces, reducing the need for manual cleaning.

<span class="mw-page-title-main">Detonator (railway)</span> Signaling system for trains

A railway detonator, or fog signal is a coin-sized device that is used as a loud warning signal to train drivers. It is placed on the top of the rail, usually secured with two lead straps, one on each side. When the wheel of the train passes over, it explodes, emitting a loud bang. It was invented in 1841 by English inventor Edward Alfred Cowper.

<span class="mw-page-title-main">Train horn</span> Air horn used as a warning device on trains

A train horn is an air horn used as an audible warning device on diesel and electric-powered trains. Its primary purpose is to alert persons and animals to an oncoming train, especially when approaching a level crossing. They are often extremely loud, allowing them to be heard from great distances. They are also used for acknowledging signals given by railroad employees, such as during switching operations. For steam locomotives, the equivalent device is a train whistle.

<span class="mw-page-title-main">Nathan Manufacturing</span> American manufacturer

Nathan Manufacturing, Inc. is a division of Micro Precision Group which manufactures Airchime, Ltd. train horns mainly for North America. It is one of two major train horn manufacturers in the United States, with Leslie Controls, Inc. being the other.

<span class="mw-page-title-main">Vehicle horn</span> Sound-making device equipped to motor vehicles, buses, bicycles, trains, trams

A vehicle horn is a sound-making device installed on motor vehicles, trains, boats, and other types of vehicles. The sound it makes usually resembles a “honk” or a “beep”. The driver uses the horn to warn people of danger. The horn is activated to warn others of the vehicle's presence or approach, or to call attention to some hazard. Motor vehicles, ships and trains are required by law in some countries to have horns. Trams, trollies, streetcars, and even bicycles are also legally required to have an audible warning device in many areas.

<span class="mw-page-title-main">Firefighting apparatus</span> Vehicle for use during firefighting operations

A firefighting apparatus or firefighting appliance describes any vehicle that has been customized for use during firefighting operations. These vehicles are highly customized depending on their needs and the duty they will be performing. These duties can include firefighting and emergency medical services.

References

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  2. "A Collection of Airhorns". Horns Inc. Archived from the original on August 28, 2021. Retrieved August 2, 2015.
  3. "WESH.com New Horns Make Cars Sound Like Trains". Archived from the original on September 19, 2008. Retrieved May 20, 2008.
  4. "The Hornster, A Bicycle With a Mounted Locomotive Horn, Breaks the Guinness World Record for Loudest Bicycle Horn". Laughing Squid. October 8, 2014. Retrieved November 14, 2020.
  5. Harris, Catharine (May 1, 2009). "Anti-inhalant Abuse Campaign Targets Building Codes: 'Huffing' of Air Conditioning Refrigerant a Dangerous Risk" . The Nation's Health. American Public Health Association. Retrieved December 5, 2010.
  6. Grossman, Evan (April 25, 2016). "The history behind the NHL's ubiquitous sound for scoring: the goal horn". nydailynews.com. New York Daily News. Retrieved August 29, 2018. The Islanders and hockey fans everywhere can thank the Chicago Blackhawks for pioneering the now-ubiquitous trend during the 1973 Stanley Cup Final against Montreal. Hawks owner Bill Wirtz liked the sound of the horn on his yacht and had it installed at Chicago Stadium..."(He) decided it would be a great thing to have in his arena," Erick Kahlenberg, vice president of Kahlenberg Industries told the Daily News...Kahlenberg's uncle Karl sold Wirtz the yacht horn and now the company supplies more than a dozen NHL teams with their own goal horns, which are the same devices you find on boats, trains, trucks and in one case, an aircraft carrier. When the Blackhawks moved from Chicago Stadium to the United Center in 1994, they took the goal horn with them. By then, goal horns had become a staple of NHL games around the league.
  7. "Red Bull Music Academy Daily". daily.redbullmusicacademy.com.
  8. Campbell, Colin (April 13, 2016). "'Air horn orchestra' seeks McCrory's attention on House Bill 2". News & Observer. Retrieved April 24, 2016.
  9. Brown, Joel (April 20, 2016). ""Air Horn Orchestra" Blasts HB2 Disapproval in Raleigh". WTVD/ABC-11. Retrieved April 24, 2016.
  10. Brown, Joel (June 1, 2016). "McCrory, Cooper Spar Over HB2; Noisy Protests Continue". WTVD. Retrieved June 1, 2016.
  11. Brown, Joel. "'Air Horn' Protesters Call Foul on HB2 After ACC's Action" . Retrieved September 15, 2016.
  12. Brown, Joel (November 2, 2016). "Final "Air Horn" Protest May Have Set a World Record Outside Executive Mansion". WTVD/ABC11. Retrieved November 2, 2016.