Paris Hilton speaks in a baby voice because she thinks it's funny.

The socialite claims her high-pitched girly voice is all an act designed to make herself laugh, and is adamant she speaks "normally" when she's hanging out with her friends or attending business meetings.
The 28-year-old hotel heiress explained: "I would do the baby voice and it's kind of like this character I made up, but in real life I'm completely different, I'm very down to earth, I'm smart, I know what's going on.
"It's kind of like I almost play to the image and kind of have a laugh at myself about it. I think a lot of people will assume that I'm just like an airhead.
"But in my everyday life, when I'm hanging out with my friends or if I'm in a business meeting I'll talk in my normal voice."
The blonde beauty made the admissions in new TV show 'Fearne And Paris Hilton', which is due to air in the UK tonight (22.10.09).
In the programme, Paris also showed presenter Fearne around her Hollywood mansion, which includes vast colour-coded wardrobes, secret passages and a private nightclub.