Since the beginning of time, man has used sound to communicate messages. From these early days the various sounds we communicated, patterns in which they were conveyed and the volume they produced had specifically different meanings to all who heard them. These principles of communication and the ability to notify someone of an important event really haven’t changed very much in all these years. The intent is the same: to notify others of an occurrence or condition. The understanding and perception of various notifications that can warn of imminent danger or create awareness of a particular occurrence or condition is vital.
In our world today the public is bombarded with so much sound, it’s hard to determine exactly what specific sounds mean. It is evident that society has become desensitized by the variety of clatter one hears throughout a day. Walking by a horn blasting without taking notice, endless beeping in the airport, the multitude of cellphone ringtones — it’s all just one great big din of NOISE!
As an industry, we also generate noise as it is often a key part of our job and a code requirement to make distinctive sounds. The sounds we produce from the fire alarm systems we install can be music to our ears, but what does it sound like to the general public? Is it loud enough to be heard? Is the message audible? Is it visually identifiable and recognized as fire alarm activation?
It is imperative that the fire alarm designer and installer be able to answer these essential questions. To do so it is important to first understand the requirements of codes associated with fire alarm system notification as it relates to design and installation.
4 Requirements for Audible Alerts
Based upon the building classification and usage, notification will differ greatly in how we display audible and visual signals. For example, a high-rise building or an area of assembly, such as a church, will require not only a visual signal but also a voice evacuation system that will deliver recorded or live instructions to the building occupants based upon the status of the fire alarm. These requirements are code driven based upon the building usage and occupancy level.
That is just one example of many types of occupancies that notification requirements must be met. Following are the primary requirements for audible notification appliances:
- A fire alarm system’s audible signal shall produce a sound level in any occupancy, 15dB above average ambient sound level in that occupancy. Average ambient sound is a measurement in a given occupancy that is measured during a 24-hour period and the average sound pressure is then figured.
- The signal produced by the fire alarm shall be synchronized. The recognized evacuation signal is a temporal 3, which produces a specific time on and time off pattern. If the synchronization is not exact the sound produced will unintelligible to the listener.
- Sleeping rooms shall have a minimum sound pressure level produced by the fire alarm system of 75dB measured at the pillow head, or 15dB above average ambient sound, whichever is greater.
- A visual signal shall be added to the notification circuit if the sound pressure levels of 105dB or greater in the occupancy is measured, or a shutdown of the source of this dB level.
Making the Public Take Notice
The essence and purpose of the audible notification signals we produce from a fire alarm control panel is to safely alert, notify and evacuate occupants of a building to safety. Early detection and notification saves lives. But there is much more that needs to be considered. Conditions of varying nature require other types of systems to be employed to alert and notify.
Sound of a varying nature will get attention. If it is distinctive from any other sound that might be in the area of notification then public awareness should prevail and take note.
As touched on at the outset, when the public encounters the sounds and signals we produce from a fire alarm control system do they understand what that noise is? Is it annoying to them? Do they decide to take action into their own hands and destroy the units that are making this noise, rendering them useless? In some cases vandalism is the only way to eliminate the sound.
Is the public unaffected by the sound the fire alarms are producing, not giving any regard to their safety? Perhaps they recite the familiar refrain, “It’s the noise from that darn fire alarm system again! It has been going off so many times that I wish someone would shut it off completely!” How many times have you heard that from someone? Complacency, lack of instruction or just complete disregard could be a matter of life or death.
Page 1 of 2 pages 1
Fire/Life Safety · Fire/Life Safety 2 ·
Audible Alerts ·
Fire Alarms ·
Voice Evacuation ·