DOCTOR: Three thousand one hundred hertz at a hundred and eighty decibels, I think.

PERI: That’s pretty loud, isn’t it? I’ll end up like a thrash metal fan.

DOCTOR: Nonsense.

PERI: I know what I’m talking about; I was at a Slayer concert once. Sounded like a jumbo jet landing in your ear. It was so loud it made my ancestors deaf.

DOCTOR: I’d no idea you were a headbanger.

PERI: Who, me? I can out-nod Noddy.