Audio fault that comes back again (3)

I believe the answer is:

wow

I'm a little stuck... Click here to teach me more about this clue!

'audio fault that comes back again' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?

This is the entire clue.

Can you help me to learn more?

(Other definitions for wow that I've seen before include "that's incredible!" , "boy" , "Amazing thing" , "Expression of amazement" , "Expression of great admiration" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.