The bus shall be equipped with a minimum of two horns of standard make, each horn capable of producing complex sound in a band of audio frequencies between approximately 250 and 2,000 hertz and having a total sound level of 110 decibels within these frequency limits when measured at a point on an axis of the horn 3 feet from the exit of the horn. The horns shall be audible to other highway users at a distance of 300 feet. If louder horns are desired, they shall be capable of producing a sound level of 120 decibels under the conditions specified above. The horn control shall be located in the manufacturer's original position.