“It's a cute acting trick, this whispering, mumbling thing. I realised a long time ago, when people are mumbling or whispering they're either talking about sex, or money, or lying. So if you're not doing that, you'd better speak up.”

Interview in The Guardian (2011)
Context: People have said, in one form or another, your diction is too good. At first you think, are you insane? And then I realised, I spent so much time in the theatre, and Mamet was such a stickler about that and I am, too – that I had been spoilt. It's a cute acting trick, this whispering, mumbling thing. I realised a long time ago, when people are mumbling or whispering they're either talking about sex, or money, or lying. So if you're not doing that, you'd better speak up.