You are so funny. I worked as a senior technician at ITT, Sprint, then MCI, and after the securities fraud, bankruptcy,(of MCI WorldCom and WorldCom), restructuring and the subsequence purchase by Verizon. I was able to retire from Verizon after 31 years.
All, of our local and long distance switching centers and wire centers were protected with high pressure Halon 1211 systems, delivered from giant tanks connected to nozzles that shot out the gas like cannons.
The Halon gas suppresses a fire by displacing all of the oxygen in a room. If a person stays in the room for over seven minutes they will get light-headed and pass out. Of course if a person is trapped in the room it could be fatal. At ITT they had a Scott Air-Pak hanging on the wall just outside the Switch room for extra safety.
One of the places where I witnessed the Halon system being tested was a wire center at 1000 Cir 75 Pkwy SE, in Atlanta across the road from what became Truist Park where the Atlanta Braves now play. Back then it was just a scenic lake with a walking path around it. We got to watch through the windows from the raised parking lot of the 1100 building when the fire suppression company did a test fire of the system. The ceiling tiles were blown down in the 80' by 50' room and debris flew all around.
Another building where I witnessed the test fire was in one of the switch rooms at the MCI Southeast Regional Switching Center. From the hallway it sounded like a freight train. I got to go into the room just after it had discharged. As I already stated, Halon displaces all of the oxygen in a room. When I walked in the room (160' by 60'), that's when I felt the absence of air on my ear drums.
The production of BCF and similar chlorofluorocarbons has been banned in most countries since January 1, 1994 as part of the Montreal Protocol on ozone depleting substances. Halon 1211 is also a potent greenhouse gas with a 100-year global warming potential 2,070 times that of carbon dioxide and an atmospheric lifetime of 16.0 years.[6]Halon was banned because it depletes the Ozone layer. So how can you claim that it doesn't displaces the oxygen when it is blasted into a room like a cannon?
I never said I had hearing loss, I said that It was an odd feeling of attenuated sound because oxygen was not reaching my eardrums.