Vacationing in Thailand as she brings in her birthday today, actress Priyanka Chopra is barely able to speak coherently. "I had to scream so hard for a sequence in Saat Khoon Maaf, I lost my voice. Now, being in the water constantly while on holiday is not going to help my throat one bit, " says Chopra, who turns 28 today.

For her roles in Ashutosh Gowariker's What's Your Raashee (12 characters) and Vishal Bharadwaj's Saat Khoon Maaf (about a woman who goes through seven different marital experiences), Chopra studied cases of multiple-personality disorder.

Now, for her role in Anurag Basu's Silence, Chopra is not only willing to learn about psychological behaviour but she has agreed to go the whole hog. Chopra plans to visit and stay at a hand-picked institution that's devoted to looking after the mentally disturbed.

Confirms a source, "At first, Priyanka was reluctant to take on the film since another leading lady (Katrina Kaif) was already on board. But when she understood the impact and nature of her role, Priyanka fell for it. She has preparing for it and intends to visit a few institutions, where she plans to spend at couple of days."

Says Chopra, "I will begin shooting for Anurag Basu's film in January 2011 after I complete Don 2. And yes, I'm setting aside time to prepare for the part. I will need special training to be adept at playing the character. How many actors from my generation get challenges like this? If I'm being given the opportunity, I better make the most of it, " she said.