You can use existing open source tools to measure SNR for noisy speech. For details see http://labrosa.ee.columbia.edu/projects/snreval/
I recommend you to try WADA SNR
http://www.cs.cmu.edu/~robust/archive/algorithms/WADA_SNR_IS_2008/
It's pretty simple algorithm but it's not trivial to design it by yourself.
Fingerprinting and ASR doesn't work for sure since they try to eliminate noise not to detect it.