It is unlawful for any person to permit the operation or playing of any loudspeaker, musical instrument, motorized racing vehicle, or other source of sound for public entertainment within a building or structure wherein the noise level exceeds ninety-five (95) dBA as determined using the slow response of a sound level meter at any point normally occupied by a customer, without a conspicuous and legible sign stating “WARNING! SOUND LEVELS WITHIN MAY CAUSE HEARING IMPAIRMENT.” (Prior code § 5090.7)