<br />Even then, yes, the atmosphere is extremely thin at these altitudes. I'm sure the sound recording system was designed to also pick up sounds through the rigid body of the SRBs --the "vibrations". <br />

Makes sense then. You can hear tapping noises at that point so that maybe because the boosters are beginning to rapidly cool off or something after the jetisson.Cheers

I thought the intermitent "swooshing" noises were interesting. I'm thinking that as the nozzles rotated through their slip stream it created an eerie vibration. Kinda like throwing a metal tube end over end. There are few frames where you can see the other SBR as it goes through a mirror image rotation with the camera mounted SBR. All things being equal, I suppose the entire sequence would be syncronized between the two SBRs. Seems the main variable would be upper atmosphere gusts and variations in the jet stream.All very interesting.