From time to time, fire technicians are asked to remove or disable audible notification appliances because they are simply too loud. Often, the reason for this is that the fire technician has oversaturated the area in question with audible devices in order to meet or exceed NFPA 72 requirements. Not only can this be annoying, it can be harmful to the ear.
So then, what procedures must a fire technician follow to minimize his or her company’s liability and maintain the life-safety properties of the fire alarm system while keeping the customer happy?

5 Steps to Uphold System Integrity
According to Moore-Wilson
Signaling Report, there are several things a fire technician can do:
1. Ask the client to submit his or her request in writing
2. Be sure to document everything, including all communications and every step taken to satisfy the client
3. Once the specified audible devices have been removed, measure the sound level of the areas in question to assure the public mode requirements of NFPA 72 are still being met
4. Another option is to have the fire alarm system automatically reduce or stop the source(s) of the high ambient noise in the affected area(s)
5. Utilize narrow-band signaling, which uses the masked threshold requirements instead of the A-weighted signaling requirements
If the client still insists on the removal of additional audible devices, a technician might ask them to make a formal request to the authority having jurisdiction (AHJ) to that effect.

NFPA’s Audible Sound Regulations
Fire technicians are required to follow the sound mechanics for audible devices as contained within NFPA 72. Because the sources of noise within the various types of facilities where fire alarm systems are installed will vary, as well as the level of ambient noise, NFPA 72 provides a general series of guidelines to follow.
For example, as outlined in Section 4-3.1.1 of NFPA 72, 1999 Edition, in environments where the ambient sound level exceeds 105dBA, visible signal appliances should be installed so the occupants will readily know when a fire is detected. When installing such devices in public areas, Section 4-4 of NFPA 72 must be followed.
The sound level of audible devices installed for use in public mode must not be less than 75dBA at 10 feet. So the occupants can hear them, Section 4-3.2.2 of NFPA 72, 1999, says the sound level must be no less than 15dBA above the average ambient sound level within the given environment, or 5dBA above the maximum level with at least a 60-second duration. All measurements are to be taken 5 feet above floor level.

Overcoming Challenging Areas
In small quarters, for example, a number of audible devices can become so loud as to be offensive to those who work or live in those areas, such as restrooms.
Most of the time, fire technicians will install strobe-only notification devices in these areas. There are some cases, however, where the AHJ or building owner may require the installation of audible devices installed. In this case, Exception 2 under Section 4-3.2.2 offers relief.
When used in private mode, audible devices are permitted to have a sound output not less than 45dBA at 10 feet, as outlined in Section 4-3.3.1. To assure audibility, the subsequent section calls for a sound level of at least 10dBA above the average ambient sound, or 5dBA above the maximum sound level with at least a 60-second duration. As in public mode, the maximum sound level allowed at minimum hearing distance is 120dBA.
Some of the audible devices made today have a selectable sound output so the fire technician can adjust it to suit the situation. In many cases, this is a much better alternative to removing audible devices entirely. If that option is not available, there are a few other tricks the fire technician can use to satisfy both code and the client.

When All Else Fails, Reduce the Level
After the fire technician has reduced the number of audible devices and/or their sound output, if the client continues to insist that additional units be removed, the fire technician might suggest the client ask the AHJ for a variance to further remove audible devices, or eliminate audible signaling altogether, within the affected area(s).
The client “may ask the AHJ to approve a reduction or elimination of audible signaling when visible notification appliances serve the facility, as permitted by Section 7-4.1.1. The contractor will need to have installed the visible notification appliances in accordance with the requirements of Section 7.5.” (The Moore-Wilson Signaling Report, Vol. 10, No. 2).
Another option is to arrange for the fire alarm system to automatically reduce the ambient noise in the affected environments. In manufacturing plants, for example, a fire alarm system can be made to turn off loud machinery, thus reducing the noise in the immediate area.
“A fire alarm system arranged to stop or reduce ambient noise, when approved by the AHJ, shall comply with 7.4.2.5.1 through 7.4.2.5.3” (Section 7.4.2.5, 2002 “National Fire Alarm Code Handbook”). This section was added to the new 2002 handbook and will be included with the next publication of NFPA 72, National Fire Alarm Code.
According to Section 7.4.2.5.1 of the handbook, the audible devices must produce a sound level that is 15dBA above the reduced average ambient noise level, or 5dBA above the maximum sound level with duration of at least 60 seconds. All measurements must be made 5 feet above floor level. Again, strobe devices must be utilized in accordance with sections 7.5 (public mode) or 7.6 (private mode).
Another possible solution, as pointed out by The Moore-Wilson Signaling Report is to utilize narrow-band tone signaling. Narrow-band signaling is outlined in Section 7.4.5 of the 2002 “National Fire Alarm Code Handbook.”

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