You can to some extent. There are a number of tools that attempt to convert from audio to note information (MIDI). As someone who's done some experiments with

You can to some extent. There are a number of tools that attempt to convert from audio to note information (MIDI). As someone who's done some experiments with those, there are some major caveats: - Most people can't sing a melody as well as they think they can. Trying to figure out what they were trying to do is where most of the effort goes. Even I'm mediocre at such, and I'm at a professional level at one instrument, and competent at a few others. - You have to deal with overtones. Almost all naturally produced notes are a stack of waveforms, and figuring out which one caries the intended signal isn't always trivial (and can be even more complicated in polyphonic harmony).