This may be an amateurish question, but is there a MINIMUM volume required for a fire detection system alarm panel (i.e., Fire Alarm Control Unit that powers and monitors various heat and smoke detectors)? I searched NFPA 72 and UL 864 and couldn't seem to find a definitive "must be equal to or greater than xx dBs" requirement. I am NOT talking about the Notification Appliances located throughout the building. I mean the panel, which certainly has its red and yellow LEDs (for visual indications of alarms and troubles) and also has an audible alarm and trouble alert. I would think that both would have a requirement that they must be above xx dBs (perhaps 70 dB?...85dB?). I understand that Notification Appliances must be x dB above their "background levels" of noise in their locations, but what about the panel? Also, is it allowable for a panel to have a volume control on its alarm and trouble audible alarms? ...perhaps allowing it to be as loud as 75 or 85 dB, but not go below xx dB (I would hope it not be allowed to go as low as 5 dB!)? If volume controls are allowed, are there any/many manufacturers that actually provide a volume control for the audible alarms and troubles, either with an old-fashioned knob or, more likely, via the panel's keypad (with an appropriate level of password entered)? Thanks.