I've been trying to learn how computers recognize musical notes, and I found apps like spectrogram which shows the frequency spectrum of a sound, but what I need is the data which is plotted or the raw data used. I'm a beginner in this field, so it'd be really great if you could help me with the software or the process used. Thanks!
An important thing to consider is that the pitch of musical notes does not directly correspond to frequency peaks in a spectrogram. This is because the energy of typical musical sounds are partially to mostly in the overtones and harmonics, at frequencies well above the note pitch (depending on the source of the music). So it would help to investigate algorithms for pitch detection/estimation, and the difference between those and the frequency spectrum of music.
Audacity has a spectrum analyser tool and you can export the data! It's open source free software, and is a great starting point if you are looking to get quick results without coding.