It’s in the code these days. From NFPA 72 - 2013.
10.13* Fire Alarm Notification Appliance Deactivation.
10.13.1 A means for turning off activated alarm notification
appliance(s) shall be permitted.
10.13.2 When an occupant notification alarm signal deactivation
means is actuated, both audible and visible notification
appliances shall be simultaneously deactivated.
10.13.2.1* When voice instructions are in progress, visible appliances
in same area where speakers are activated shall also
be activated where required by the emergency response plan.
(SIG-ECS)
In the explanatory material there’s this:
A.10.13 It is the intent that both visual and audible appliances
are shut off when the notification appliance silence feature
is activated on the fire alarm control unit.
Per the ADA, it is important not to provide conflicting signals
for the hearing or visually impaired.
A.10.13.2.1 The intent to activate the strobes while voice instructions
are being provided is to alert the hearing impaired of
the fact that information is being provided and they should use
the visual indication as an indication to seek out information.
So not only do both have to go off, but when manual voice control is being used the strobes in that area have to come back on.
MyTechTime is spot on.
Similar verbiage exists in the NFPA 72 - 2010 and 2007. The 2002 code allowed audible silence, but left it up the AHJ to decide if visuals would be shut off too or not. Now, it’s important to note that prior to 2007 the ADA had their own guidelines we had to follow so there were two separate codes to follow for this so to speak, in 2007-2010 they finally aligned them with the NFPA 72 to eliminate any confusion. This means the ADA might have had these requirements all along, despite what the 2002 code stated, but I’m not aware of it.