How do car horns make sound?
Car horns have a flat circular steel diaphragm that has an electromagnet pulling on it and is attached to a contactor that repeatedly interrupts the current to the electromagnet, somewhat like a buzzer. There is usually a screw to adjust the distance or tension of the electrical contacts for best operation. A spiral exponential ‘snail’ horn shape is built into the body of the horn to project the sound effectively. Sound levels are about 107-109 decibels, and they pull about 5 or 6 amps. They can be used singly, but are more often in pairs to produce a chord consisting of two notes, sounded together. This only increases the sound output by 3 decibels, but the use of two differing frequencies with their beat frequencies and missing fundamental is more perceptible than the use of two horns of identical frequency, particularly where there is a high ambient noise level. Typical frequencies of a pair of horns of this design are 500 and 405-420 Hz (approximately B4 and G#4). Some cars, and ma
