Is the report of an explosion exclusively from the implosive inrush effect?

I can concur that there IS an implosion sound, as I hear it when a blow torch is turned off. Sounds like a firecracker. But a blow torch doesn't involve a mive supersonic out rushing of ges, which must themselves create out rushing shock waves that should contribute to the audible event. I read an explanation that shock waves from a supersonic object disappear when it returns to subsonic speed, & does not detach, & move ahead as a continuing but diminishing sound wave. Does the same rule apply to an out-rushing blast front? Why does the outflow not produce sound while the inflow DOES? From what I've seen in nuclear test footage, the inflow doesn't "wait" for the outflow to reach its limits, so I would not be surprised if the out flow contributed an "explosive Lens" effect-really slamming in on the center of initiation. I mainly want to know if the out rushing blast contributes to the noise.