I use audacity. You can slow it down without changing the pitch. You can also play around with the spectrum analyzer, sometimes it can help you pick out individual notes. You highlight the part of the wave containing the note you want and go to Analyze -> Plot Spectrum, and if you are really lucky, there will be a big peak somewhere and when you put your cursor on it, you should see the note down below the graph. There's probably better ways to do that, but it has worked for me a few times.
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