I highly doubt a commercial plane is 90 dB in the cabin continuously. If that were the case, all passengers would suffer hearing damage on long flights. Maybe at takeoff and landing?Is there a difference in terms of hearing damage when listening to a sports car at 80 dB and being on a plane at 80 dB? Why would a sports car cause a permanent spike but airplane cabin noise wouldn't? When I see people using sound meters on a plane on YouTube, sometimes it's reaching close to 90 dB. Is cabin noise less damaging compared to other sounds at similar dB levels due to it being a lower frequency?
Regarding car vs. plane, there should be no difference. All I know is my ears are more susceptible to damage, so I now protect them in both scenarios. I had no protection in the car when the permanent damage occurred. Also, that 80 dB number is just an estimate - it could have been higher when revving the engine, driving on rougher pavement, etc.