How to compare two analog signals (piano notes)

Question

I am working on a project:

A mobile application which will

1. Record a student's play (student's play from the physical piano and not the Midi/virtual piano)

2. Compare it with the master's play and then display a report.

3. The report will indicate the mismatch of tones, pace, notes, etc.

Trial:

I tried to convert the analog signals (student's play) into the digital signals and then start comparing them.

But it didn't work well. The comparison didn't work as expected. It couldn't take multi variables needed for the report and thus gave a wrong report.

Any other ideas how to do the above task?