So is it similar to dreaming?
Also, what do you mean by "sound"? Like music or actual sound from your memories?
I’ve had similar experiences.
In my case it wasn’t like dreaming exactly, more like that in between state where you’re falling into a nap but still awake. Sound was kinda like being underwater, in fact recovering consciousness very much felt like surfacing into reality for lack of a better term.
It was kinda cozy, definitely not an experience to be scared of.
Part of it has to do with the memories, which gradually gets overtaken by the voices of my wife, doctor or whomever was trying to wake me up.
As an example, I think I was around 16 years old and I was very much into sport cycling and Tour de France. When I lost consciousness a slide show of Tour de France competition accompanied by the TV commentators rush into my thoughts. All of it at very high speed and extremely overwhelming.
I think of it as an analogy of a memory dump of a process that is no longer running (consciousness), and everything gets just read and dump at high speed and without any sense nor capacity to make sense of it, only leaving a small impression in my short memory area which afterwards I was able to remember for longer time.