It shall be unlawful for any person to operate, or permit to be operated, any loudspeaker or other device for the production of sound in any place of public entertainment or other place of public assembly which produces sound measure levels of ninety (90) dBA of greater at any point that is normally occupied by a person, unless conspicuous and legible signs are located outside such place, near the entrance, stating "WARNING, EXPOSURE TO SOUND ENVIRONMENT WITHIN MAY CAUSE HEARING IMPAIRMENT."