I hope Windows is good for this, but I’m not sure. I have spent hours looking for a solution, and so far I’ve only found two options that seem promising. One is the online services I mentioned above. The other is a command line method available in Linux. Installing Linux (and learning again how to use it) to fix this problem sounds a bit overkill, but I would do it if it turns out it’s the only method that works.
Anyway, I have Audacity installed in a machine running Windows 7 Home Premium SP1. I made the recordings with an Android smartphone.