Ugh, that is annoying.
Makes me think of a pet peeve of mine. Say he's in the kitchen (at the back of the house) and I'm in the living room (front of the house) and while they are not far from each other, it can be hard to hear each other when calling to each other across the house.
So inevitably, this occurs.
DH: Pirate, could you-
Babe: NANANANANANANA!!!!!! Boys: Leave me alone, I'm trying to get this done!/I'm not doing anything to you!"
Me: I didn't hear you, what was that?
DH: Boys, be quiet. I said could you-
Babe: DADADADADABABABA!!!!
Me: Just come in here and tell me what it is.
Okay so you get the idea, conversations cannot be held across the house, since while we can ask the older two to be quiet, the baby doesn't know what "hush" means.
Yet see what happens in reverse:
Me: Hey honey, did you talk to your mom to see when she was coming up?
DH: What? I couldn't hear you over the running water, you know we can't hear each other across the house!
Two days later:
"Hey, Pirate, did you get any more g-"
BABABABA!!!!!!!!!!
"...nevermind."