[higgmeister]

In my telecommunications career I worked in a large number of Switching centers and wire centers all protected by Halon gas.   I even had the pleasure of going into rooms that had a test Halon gas dump.   The absence of oxygen in the room gives a bizarre sensation with sound not reaching your ears.

Halon Fire Extinguishers: Halon extinguishers, although less common due to environmental concerns, are highly effective in suppressing electric vehicle fires. Halon gas works by interrupting the chemical reaction of the fire, effectively extinguishing the flames.

The stupid people who purchase a Tesla for environmental concerns, also would not protect themselves with Halon gas because of environmental concerns.

[Moltke]

The absence of oxygen in the room gives a bizarre sensation with sound not reaching your ears.

Only in a vacuum does sound not propagate (remember the Aliens catch line?) due to a lack of a "carrier". In all matter and material it does. Whatever caused your hearing loss, lack of oxygen (only ~21% of air anyway) was not it.