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What is an Air Horn?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

An air horn is a horn which uses compressed air to create a very loud noise. Big trucks and emergency services vehicles use air horns to alert other drivers to their presence, as do trains and ships. Air horns are used at sports events since their volume level is high enough to be heard over loud audiences of fans. Some people also use personal air horns at sports games, or on their own vehicles, although the use of air horns on cars may not be legal in all regions.

A basic air horn includes a chamber of compressed air which is attached to a valve which allows air to pass through it into a resonant horn. You could think of an air horn as a souped up brass instrument, since these horns work on the same principle. Just like a trombone or a trumpet, an air horn can be calibrated to generate specific notes or tones. In some parts of the world, specific notes are reserved for particular classes of vehicle, and trains actually produce chords, not single notes.

Avoid using an air horn in residential neighborhoods, as it may trigger a noise complaint to law enforcement.
Avoid using an air horn in residential neighborhoods, as it may trigger a noise complaint to law enforcement.

The distinction between different air horn sounds allows people to know not only that something big is approaching, but what that something is. If you hear a chord, for example, you know that a train is on the way, while a stuttering tone is used on emergency services vehicles like fire trucks. On ships, air horns can be used as signals to communicate with other ships in the dark or in poor visibility conditions, when ships might not be able to see each other until it is too late to avert an accident.

Air horns are commonly heard at professional sporting events.
Air horns are commonly heard at professional sporting events.

The air horns used on trains and ships are quite large, and capable of generating a formidable sound. Personal air horns like those carried to sports games are much smaller; they typically consist of a canister of compressed air and a modest horn which can make a loud but not deafening toot. A personal air horn can also be used as a safety device; joggers, for example, could carry air horns to scare off would be attackers.

Joggers may benefit from carrying a personal air horn for protection.
Joggers may benefit from carrying a personal air horn for protection.

The use of air horns on personal motor vehicles like cars and trucks is often restricted or outlawed. This is because the use of air horns on non-commercial vehicles could be confusing or distracting for other drivers. This could potentially pose a danger. For drivers who cannot resist the temptation to install an air horn, moderation is advised; horns should really only be used in emergency situations. You may also want to consider avoiding the use of an air horn in residential neighborhoods, as this could trigger a noise complain to law enforcement.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

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    • Avoid using an air horn in residential neighborhoods, as it may trigger a noise complaint to law enforcement.
      By: studiovespa
      Avoid using an air horn in residential neighborhoods, as it may trigger a noise complaint to law enforcement.
    • Air horns are commonly heard at professional sporting events.
      By: duncanandison
      Air horns are commonly heard at professional sporting events.
    • Joggers may benefit from carrying a personal air horn for protection.
      By: Marco Antonio Fdez.
      Joggers may benefit from carrying a personal air horn for protection.