This provision is an "emission" control that limits the activation period of alarms and restricts activation to a specific time-of-day or day-of-week. Los Angeles, CA () prohibits the sounding if the signal can be heard at 200 feet or more. Chicago, IL (Section 11-4-2820) considers the sound to be a noise disturbance in residential areas if the sound exceeds 5 minutes in any hour; steam whistles are exempt. Albuquerque, NM (Section 9-9-12) restricts levels to 5 dB over the ambient at a property line and applies maximum permissible residential level as well as "plainly audible" restrictions at night.