Dave,
I remember reading "Hiroshima" years ago and being impressed by that
fact. As I remember the nearest person to the blast that reported hearing
the sound was a farmer out in the countryside. Also if memory serves people
near the Mt. St. Helenes blast did hear it as well - It seems to be common
to large explosions. I suspect that the supersonic pressure shockwave from
the blast is great enough to so overload the ear drum that nothing is heard
- To hear sound, vibrations are necessary to excite the hairs in the cochlea.
I hope this helps.
Gary
Gary Karshner
St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU