Shailene Woodley learned to sing "outside of the shower" while making a Janis Joplin biopic.

The 32-year-old actress has revealed that she discovered the full extent of her singing talents while she was preparing to star in the upcoming biopic.

Shailene said on 'LIVE with Kelly and Mark': "I'm not like a trained singer, but I feel and I can sing in my shower.

"It turns out I can also sing outside of the shower, which I didn't really know until I started working on the Janis project, and working with Linda Perry, who's an amazing music producer and musician herself.

"She's really encouraged me and helped me find my centre and my own voice, which is incredible."

Shailene jumped at the chance to star in the biopic, explaining that she's a huge fan of the iconic musician, who died in October 1970, aged 27.

The Hollywood star said: "It's been really exciting. It's been over six years of putting it together.

"To me, it's important to do these things with a lot of integrity and a lot of care. Janis is someone I've always deeply respected and admired, like the spirit in her, the soul she was on this planet and kind of the light that she was on this planet."

Earlier this month, Shailene revealed that she was previously forced to reject a series of roles because of a "debilitating" health problem.

The actress told The Hollywood Reporter: "I said no to a lot of projects, not because I wanted to but because I physically couldn’t participate in them.

"And I definitely suffered a lot more than I had to because I didn’t take care of myself. The self-inflicted pressure of not wanting to be helped or taken care of created more physical unrest throughout those years."