Why are fire alarms so loud?


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?

How loud

There’s a fire safety guideline called NFPA 72 and it basically covers all the requirements for fire alarms. Obviously there are two components to a fire alarm – their physical appearance (visible) and second, the sound the alarm makes.

According to NFPA 72, horns and sirens sound an alert at 65-120 decibels when you’re standing 10 feet from a device. Now that creates a quandary for health inspectors because prolonged exposure to loud noises can harm your hearing and that in and of itself is really, really bad.

So to balance that off, we have:

Varying degrees of volume 

A fire alarm’s job is to let everyone in the building know that they need to leave immediately. That’s why the noises are allowed to be louder than most.

The exact requirement is usually 15 dB above the average noise level or 5 dB above the maximum ambient sound – whichever is greater. So what does that mean? It means the noise needs to be greater than the surrounding noise. So 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 and equipment is going off everywhere – they usually crank it all the way up to the max dB. Why? Because everyone needs to hear it.

So that’s why some alarms are louder than others.

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.

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