Ok. I work in tv. I sometimes direct voiceovers. I worked one place where the audio suites were tucked away in the depths of the basement. It was less than glamorous and always slightly eerie.
The voiceover sits in a separate soundproof booth while I sit in the audio suite next door with the audio guy and maybe someone from production (if you need a reference, look up the toast of London!). The voiceover has headphones on and through them can hear the tv showing whatever they're recording against, plus talkback from our room so she can hear us chatting and giving feedback. Unlike toast and other swish places in Soho, in this dive we can't see the voiceover from our room so we have to rely on talkback.
We start recording. All going well. Then she starts talking to herself a bit in between takes. We're amused but don't think much of it. (I could start an entire thread on things actor people have done). Then she starts to go a bit quiet. Misses a few cues. Seems a bit flustered. And says - stop saying that. It's not funny any more.
At this point none of us are talking. And even if we were, the talkback wasn't even on as we were in record mode. Audio guy asks whats up. And she's really upset by this point saying - what do you mean what's up? stop whispering at me.
Audio guy and I just look at each other. We weren't whispering. And nothing on the tv could be described as whispering. I tell her this on talkback and she just starts crying. Audio guy dashes off to the booth to find her a sobbing mess. I can hear them as she freaks out saying she could hear a man heavy breathing and whispering to her in her headphones.
He brings her back in our room. She hasn't finished the job but there's no way she can go back in there. Audio guy sits in the booth for a bit with the headphones on and we chat through talkback to see if he can hear. Nothing. Just us.
She says she thought it was one of us messing around. (We knew her quite well. She was a regular so we would always chat and have a fun session). It started off just saying hello. I can see you. Then got creepier with heavy breathing and sounding menacing.
Then we listen to the recordings of her voice. And in between her talking, if we boosted it up, I swear we could hear something. Someone whispering
We never got to the bottom of it. As far as I know it didn't happen again in those suites but then I left soon after so thankfully never had to go down there again.