I've read stories about husbands listening or watching from hiding places while their wives have sex.  
They usually hide in the closet or in another room or outside. I read one about the husband being under the bed.  That sounds far fetched to me. though. I think it's internet bullshit. 
We've talked about doing something like that. It might be fun. Since all of the men that we've brought here knew I was married and were aware of my husband here it was never something that we thought about.
I do take my lovers into the bedroom alone, and my husband listens.  But he's not hiding. The other guy knows he's here, so I guess it wouldn't be the same.
We have talked about me bringing someone over, letting them think they're alone with me. I do have a big walk in closet.  My husband could hide there.  But under the bed is out for me. I would be too nervous to fuck, knowing my husband is underneath the bed and could sneeze at any moment! :0)
But the closet might be fun.  He said he'd give a go if I wanted to. So maybe that's something I will be able to blog about one day.
We'd have to set up a place in there for him to sit and listen. I'll make sure to set him up on his side though. I don't want him to ruin any of my clothes if he gets carried away whacking off while he's listening to me fuck!