Re: why don't we hear a sonic boom shortly after the space shuttle launches?

The Shuttle hits Mach 1 while flying over the Atlantic Ocean; thus the 
shock wave impinges the Earth, causing a pressure differential, over the 
ocean's surface, and not on land near the viewing area.  If a portion of 
the shock wave were to pass over the visitor's viewing area, it would be 
inaudible due to the noise level of the SRMs (Solid Rocket Motors).

-Dennis