dunno. The sea-level 20 deg C number is 761.2 mph which he didn't reach. May just have gone fast enough to reach the Mach 1 speed of the cooler air he was falling though.
It varies, so depends how fast he was going and where it was: http://en.wikipedia.org/wiki/Speed_of_sound#Altitude_variation_and_implications_for_atmospheric_acoustics
@hippy started
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It varies, so depends how fast he was going and where it was:
http://en.wikipedia.org/wiki/Speed_of_sound#Altitude_variation_and_implications_for_atmospheric_acoustics