Everyone knows that fire alarms are there for our own safety and thank goodness they are. But a question we always get is why they have to be so loud – or maybe more precisely – why they have to be so piercingly loud.
If you’ve ever been to a rock concert or heard a fighter jet up close – there are some sounds that just feel like they not only physically hurt – but go right through your head and into your body. Safe to say – some fire alarms can feel like that. Why?
The purpose of fire alarm Notification Appliances is to provide stimuli for initiating emergency action and provide information to users, emergency response personnel, and occupants.
There’s a fire safety guideline called NFPA 72 and it basically covers all the requirements for Fire Alarms. There are two characteristics to a fire alarm Notification Appliance – Visual (Strobe) and Audible (Horn, Siren, Speaker).
Per NFPA 72, The total Audible sound pressure level produced by combining the ambient sound pressure level with all audible notification appliances operating shall not exceed 110 dBA at the minimum hearing distance.
This may cause some concern to exposure of high sound levels. As the table shown below indicates, harm may come after exposure to maximum allowable level of 110 dBA in excess of 23 minutes. You should have evacuated the building and be in your pre-designated rally point well before 23 minutes.
Varying degrees of volume
To ensure that audible public mode signals are clearly heard, they shall have a sound level at least 15 dB above the average ambient sound level or 5 dB above the maximum sound level, whichever is greater.
So, what does that mean? It means the alert sound output shall be greater than the surrounding noise. For example, if you’re in a restaurant – you want the alarm to be heard above the background noise, talking, music, clanking of plates and the like. If you’re in a factory where it’s incredibly loud with the operations of machinery and production – the fire alarm sound level is pushed to the maximum allowable.
Anything I can do to protect my own hearing?
Covering your ears should work just fine. The most important thing you can do is to make sure you have a fire evacuation plan and regularly hold fire drills. That way everyone knows what they need to do in order to evacuate the building in the worst-case scenario. Just by doing that alone, you’ll limit the amount of exposure to loud noises.
Also, if you think your alarms are too loud, then give a company like ours a call and we’ll come help adjust it for you in compliance with the NFPA 72 regulations. It’s important that you never tamper with your own alarms. The NFPA has these codes for a reason and disconnecting or adjusting the volume of your alarms could result in fines, code violations – or worse yet – someone gets hurt.