A couple year ago, I was listening to music at a super low volume (way below that of people talking around me, if I removed the headphones) when fire alarm triggered. I didn't hear it.
A coworker did pat my shoulder to let me know, and I noticed the super loud fire alarm as soon as I removed the quiet headphones.
The headphones were not noise-cancelling or anything. Just Sennheiser HD380 Pro, which provide ~30dB isolation. I don't think it would have been possible for fire alarm to be noticeable under such conditions unless it was loud to ear-damaging levels.
This suggests that alternative indicators than just sound should be in place, such as automatically turning off lights and switching to emergency lighting.
Small children have this problem when they are sleeping. They just don't wake up from high-pitched noises, but require lower frequency alarms ideally with spoken words: https://www.bbc.com/news/health-38918056
I wonder if this is an adaptation to not be woken up by infants crying at night until they're old enough that sleep isn't as important or they're able to help?
>This suggests that alternative indicators than just sound should be in place, such as automatically turning off lights and switching to emergency lighting.
The commercial building fire alarms have flashers on them for just that reason. Deaf people need to know the building is on fire too.
At one of my former workplaces we weren't allowed to wear over-ear noise cancelling head phones because of the risk that we didn't hear the fire alarm.
