For example, suppose a spaceship explodes. The sound of the explosion will travel in the expanding cloud of escaping gas. I gather that it should rapidly weaken and the pitch should drop, but I'd like to get more specific than that. Are there any models that suitably describe precisely this sort of situation?
Additionally, is it feasible for there to be a relatively safe distance away from such an exploding spaceship where the expanding gas cloud isn't yet extremely rarified and an audible sound might actually be heard through your space helmet?