In this article, unless the context otherwise requires:
a. "Commercial purpose"
shall mean and include the use, operation, or maintenance of sound-amplifying equipment for the purpose of advertising business, goods or services, or for the purpose of attracting the attention of the public to, or advertising for, or soliciting patronage to or for a performance, show, entertainment, exhibition or event, or for the purpose of demonstrating any such sound equipment or for the purpose of paging employees or customers.
b. "Emergency work"
shall mean work made necessary to restore property to a safe condition following a public calamity or work required to protect persons or property from an imminent exposure to danger.
c. "Motor vehicle"
shall mean a motor vehicle as defined by the California Vehicle Code.
d. "Non-commercial purpose"
shall mean and include the use, operation or maintenance of sound equipment for other than a commercial purpose. Non-commercial purpose includes philanthropic, political, patriotic and charitable purposes.
e. "Sound-amplifying equipment"
shall mean a machine or device for the amplification of the human voice, music, or any other sound. Sound-amplifying equipment does not include:
f. "Sound truck"
shall mean a motor vehicle regardless of motive power, whether in motion or stationary, having sound-amplifying equipment mounted or attached to it.