I remember reading this in maybe the late 1980s, and I have a strong inclination that it was Bradbury. I remember checking out a Bradbury collection and reading a bunch of those stories around that time. I'm sure I read "A Sound of Thunder," though I looked at the stories in Golden Apples of the Sun and I don't see anything there. I also looked at all the stories in The Illustrated Man, and don't see anything that looks right either.
I suppose the closest thing is "Kaleidoscope", but I don't see anything in that story about radio waves and TV broadcasts being trapped in a cloud.
I'm starting to think it's not Bradbury, and I had also picked up some random Sci-Fi anthology around the same time.
Added stuff I can think of (but not confirm):
It takes place entirely in space. There is the pilot of a spacecraft who either leaves his ship because it's disabled (out of fuel or something), or he becomes separated from the ship while investigating something. He encounters this cloud or nebula type entity.
It's possible that the transmissions somehow appear to the pilot and crew, and they go seeking them out to find out what it is. It's possible that they do not see the transmissions ahead of time and the pilot simply discovers the entity.
When he discovers the entity, he hears voices and music and wonders what is trying to be communicated. Eventually, he realizes that sound is not communication, but just TV programs and radio programs from earth that are "trapped" inside it, and they are playing over and over like distant echoes, or possibly it's just receiving the signals very late after they were transmitted.
One more added idea is that it could have been a radio drama or a novelization of a TV show like The Twilight Zone or The Outer Limits. When I was young, I had a book-on-tape machine that I played all of my books on because I had dyslexia and was able to get that machine from our local library. It's possible that some of the tapes on offer were not from books 🤷♂️, though I can't say exactly. I just wanted to open this up for anyone who remembers a radio or TV show with this plot in it.