Calculate the SNR of wav file?
When you dont have the exact voice as a reference you can only go to estimate/measure the noise. Assuming you are facing white noise, the simplest thing is to look for either time-domain or frequency-domain parts of the signal, where no voice is present. In these parts there is only noise. Hence, if you measure the average signal power in these parts, you get the noise power P(noise). Then, you measure the overall signal power, which is P(voice) + P(noise). Finally, you can have
$$ SNR=\frac{P(voice)+P(noise)-P(noise)}{P(noise)} $$