Sienna Miller likes ''disappearing'' into her acting.

The 'Loudest Voice' star admits there is ''real peace'' in immersing herself in different roles as it allows her to ''turn down the noise on her own life''.

Speaking to the Daily Telegraph newspaper, she said: ''It's very relieving ... turning down the noise on your own life and shifting the focus to what it would be to be someone else. You do cease to exist. There's real peace in that ... I also do like being myself. I'm not filled with self-loathing and trying to escape it, but I just ... I like disappearing.''

However, there is one role Sienna would refuse to play - ''someone's wife''.

She said: ''This is the first time I've been in every single scene of a film. I really liked it. I'd spent so much time trying to make the most of things that weren't quite there. There were some really great movies with great directors, but I was really always trying to do something interesting with nothing. To finally be in charge of something, to tell a story and map the entire thing, was really great. I'm 37 years old. I'm ready to do that. I don't want to be someone's wife, trying to embellish some role that's really nothing. I won't do that anymore.''

And the 'Factory Girl' star thinks she's been ''underestimated'' throughout her career.

She explained: ''I do feel like I've been, for much of my life, underestimated.

''If you do something that starts to tackle that and stop allowing that underestimation, that's a huge personal thing. It's really lovely.''