An automobile horn, can be divided into a motor pump speakers, electronically controlled air horn, air horn machinery. Electric air horn produced by the DC motor pump compressed air through the compressed air hose to import gas flame horn sounding device (copper plate, silica gel plate or tray) audible, and then expand the amplified sound via the mouth, reaching warning, caution role. Electronically controlled air horn from the two to four or more flare, provides air pressure, car horn switch control switch is powered by the car even comes with an air pump (pump the brakes or electric pump), as shown only an electrically controlled air horn. Mechanical devices and other air horn air horn pronounce no difference, just by the electric air pump changed manually, mainly for lack of power of the local football playing field, cycling and other fans set.