Did Sirius Black actually laugh?

When Sirius was framed for the death of Pettigrew and the Muggles - did he actually laugh or was that something made up to make him look even more insane?

Did he actually laugh? Yes, I would say he did. 

Well, he did, because I’ve created him. Sirius, to me, he’s kind of on the edge. 

Do you not get that feeling from Sirius? He’s a little bit of a loose cannon.

I really like him as a character and a lot of people really liked him as a character and are still asking me when he’s going to come back. [laughs] But Sirius had his flaws – I’ve sort of discussed that before – some quite glaring flaws. I see Sirius as someone who was a case of arrested development. I think you see that from his relationship with Harry in Phoenix. He wants a mate from Harry, and what Harry craves is a father.

Harry is outgrowing that now. Sirius wasn’t equipped to give him that. The laughter – he was absolutely unhinged by James’s death. Harry and Sirius were very similar in the way that both of them were craving family connections with friends.
So Sirius with James wanted a brother, and Harry has nominated Ron and Hermione as his family.

This is the thing I found interesting. It might have been on MuggleNet’s comments. This is a while back when I was actually looking for fansites of the month (or whatever arbitrary time period I do). It was around the time I was reading comments for the first time, and there was something in there where kids were saying,
“I don’t understand why he’s shouting at Ron and Hermione. I mean, I’d shout at my parents; I would never shout at my best friends.”
But he has no one else to shout at. That was interesting from young kids because I just don’t think they could make that leap of imagination. He’s very alone.

Anyway, I’ve wandered miles away from Sirius. He was unhinged. Yes, he laughed. He knew what he’d lost. It was a humorless laugh. Pettigrew, who[m] they, in a slightly patronizing way – James and Sirius, at least – allowed to hang around with them, it turned out that he was a better wizard than they knew. Turned out he was better at hiding secrets than they knew.


MUGGLENET.COM INTERVIEW WITH JO ROWLING (2005):
http://www.mugglenet.com/j-k-rowling/jkr-interview-mugglenet-leaky-cauldron/