Converting an MP3 audio file to sheet music is a difficult process which requires specialized software. There are no free programs to convert MP3 to MIDI, the first step in the process, so you'll have to purchase a program such as WIDI Recognition System Professional. (They offer a free trial version, but this only allows you to save ten seconds of music.) Converting the MP3 to sheet music in this manner, although the results are not perfect, is easier than trying to transcribe the entire song by ear.
Download and install WIDI Recognition System Professional (www.widisoft.com).
Open the program. Under "Select Action," choose "Transcribe Pre-recorded MP3, Wave or CD." Click "Next."
Click "Browse." Locate the MP3 file you want to convert, highlight it and click "Open." Click "Next" and wait for the program to analyze the audio.
Click "Settings" to adjust the recognition settings, or click "Next" to use the default settings. The program will convert your MP3 to MIDI. Click "Finish" to view your file, then "Save."
Download and install MuseScore (www.musescore.org), a free music notation software. You can also use Finale, Sibelius or any other music notation software that allows you to open MIDI files.
Click "Open" and select your converted song. Choose the smallest note value in the piece. This will affect the time signature. If you're not sure, experiment with different options until the time signature makes sense.
Edit the music notation. Since MP3s are more complex than MIDI files, important information such as instrumentation and voicing may have been lost. However, you have all the notes. All you must do is assign them to the right musical part, as well as add information such as tempo markings and lyrics.
WIDI cannot recognize different instruments, so it will produce a MIDI file that sounds like a piano.