Vehicle horn England, developed a standard electric car horn in 1910. Car horns are usually electric, driven by a flat circular steel diaphragm that has an electromagnet acting on it in one direction and a spring pulling in the opposite direction. The diaphragm is attached to contact points that repeatedly interrupt the current to that electromagnet causing the diaphragm to spring back the other way, which complete the circuit again. This arrangement opens and closes the circuit hundreds of times per second which creates a loud noise like a buzzer or electric bell, which sound enters a horn to be amplified. There
French horn the assistant is asked to play a passage after resting a long time. Also, he or she may be asked to enter in the middle of a passage, exactly matching the sound, articulation, and overall interpretation of the principal, thus enabling the principal horn to rest a bit. The French horn was at first rarely used in jazz music (Note that colloquially in jazz, the word "horn" refers to any wind instrument). Notable exponents, however, began including French horn in jazz pieces and ensembles. These include composer/arranger Gil Evans who included the French horn as an ensemble instrument from the