(a) As used in this article:
(1) Sound Truck: Any vehicle, having mounted thereon, or attached thereto, any sound amplifying equipment.
(2) Sound Amplifying Equipment: Any machine or device for the amplification of the human voice, music or any other sound. "Sound amplifying equipment" as used herein shall not be construed as including standard automobile radios when used and heard only by the occupants of the vehicle in which installed, or warning devices on authorized emergency vehicles, or horns or other warning devices on other vehicles used only for traffic safety purposes. (1963 Code § 27.701)