Thread Subject: Speech and SNR

Hi!

I'm trying to solve this problem: I have a speech signal for witch I'd like to compute SNR. I found something about it when you know what the noise is (standard deviation, etc.). But I don't have this information, so I can't use equations with these values. Is there any way to obtain them from that speech signal? Or is there a way to compute SNR by another method?

Thanks for anythig!