You can definitely hold a conversation while using it, put it that way. ;) It's definitely not what I'd call loud: it didn't wake DH up when I had to pump at 2am, and wasn't intrusive when I had to pump at work - all good.
There's a video on YouTube that may give you an idea - not too sure, we're watching a movie so can't check it out too loudly. ;)
Swing pump noise