A standard smoke detector’s alarm is loud enough so that everyone should be able to hear it, right?
Unfortunately, that’s not the case for lots of people with hearing loss. Most smoke detectors have a very high-frequency fire alarm, which is bad news for most people because it’s the high frequencies that people tend to lose first.
The State of Smoke Detectors
Regulations vary depending on where you live, and some require that smoke detector alarms go off at a minimum of 75 decibels. There are no regulations for which frequency they should sound at, but most alarms sound off at 3100 Hertz. In comparison, most speech is around 1000 Hertz so a 3100 Hertz alarm has a sound that’s much higher.
Clearly this presents problems for someone with hearing loss in the high frequencies. So why do alarms have such high frequencies? It’s mostly because of size issues. To be small it needs a small speaker, and smaller speakers can’t put out low-frequency sounds at a high enough volume.
Who does this affect? Millions of people with hearing loss, as well as those who have hearing aids or cochlear implants but take them off at night.
A study tested how individuals with high-frequency hearing loss could hear smoke alarms. It found that a standard smoke alarm went off, participants would wake up only 56% of the time. Increasing this volume meant that participants would wake up about 84% of the time. At least 16% of participants didn’t wake up when a louder-than-normal alarm went off.
A Better Solution
The best way for a fire alarm to wake someone is by playing a sound that they can hear. This might sound like an obvious statement, but take everything that we’ve said above. Even if it seems like a loud, high-frequency, sound is the best, for many people with hearing loss that’s just not the case.
There have been some other options that don’t use sound, but most of them aren’t very effective. That study found that bed shakers or pillow-shaking alarms woke up only about 80% of people with hearing loss in the high frequencies. The same study found that strobe lights could wake up only about 27% of the individuals.
The best solution so far has been a smoke detector whose alarm plays a low, 520 Hertz, sound. When loud enough, this will wake up 100% of participants and often does so within 10 seconds. That means even people with hearing loss in the high frequencies will be able to hear the alarm.
There’s really only one downside to low-frequency alarms: size. 520 Hertz alarms tend to be larger than their higher-frequency counterparts. But 40% of fire fatalities died even when a fully working smoke detector was nearby, so getting a slightly larger smoke alarm is probably a good idea.
Do you have hearing loss? Get more info like this by subscribing to the MED-EL blog!