[userbinator]

NIOSH says 15 minutes at 100dB, which is still far longer than the combined duration of all announcements on a flight.

http://www.sengpielaudio.com/PermissibleExposureTime.htm

I think the 99dB value the author of the article measured is not arbitrary - and was chosen specifically to meet some regulations.

[kissickas]

That depends on the flight. I've timed the announcements on some medium-length flights totaling upwards of 30 minutes.