Responding to a fan question via Twitter, Penello said the following:
@LikChan It’s DEAD SILENT. Quiter than the new slim 360’s.
We aren’t going to take him word for word – it can’t be dead silent, but we are going to say that you can expect not to hear it when playing a game. This will be good news to those of us who had loud Xbox 360s. Also given the Xbox One’s multimedia capabilities, in addition to playing (loud) games, having a quiet system will be nice.
@LikChan It's DEAD SILENT. Quieter than the new slim 360's.
— Albert Penello (@albertpenello) August 16, 2013
If you want to know just how loud the Xbox 360 could sometimes get, check out this Youtube clip…
Here’s to quieter consoles!