Air horn: Encyclopedia - Air horn

Air horn

The air horn is a device designed to create an extremely loud noise. It is usually composed of a pressurized air source coupled to a horn through a valve which allows the device to be turned on and off. Air horns have been installed on large semi-trailer trucks for many years.

More recently, some individuals are adding truck air horns (and even louder train whistles that sound a minor-seventh chord rather than the major chord of truck horns) to their personal autos as a hobby or addition to the culture of bigness exemplifed by SUVs.

It should be noted that the use of a train whistle in an automobile could cause an accident.

The reverse has been noted, in which:

  Original diesel locomotives did not have whistles,
  but were equipped with truck horns. After the accident, the bus driver
  exclaimed that he had heard the train, but had thought that it was a
  truck. link

Portable air horns are also readily available, utilizing a small aerosol spray can as the air source. These are often present at sporting events such football and soccer, and at other outdoor events.

Adapted from the Wikipedia article "Air horn", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki