A long time tradition for learning how to play like the great soloists is to learn their solos from recordings. Ideally, you would listen to the recording slowed down. However, on analog equipment, when you slow down the recording, you have to adjust the pitch back up, since you have effective dropped the frequency of the recorded notes. With mp3 files, you have the advantage of having sampled the original recording into discrete chucks called frames. Thus to slow down a recording, you can just tell your music player to double the number of times it plays each frame, and you have slowed down the playback without affecting the pitch.
Say you are a harmonica player and you want to learn John Popper’s solo at the beginning of Runaround. You can do so by playing it back in mpg123. Here’s the approach I would use. Start by playing the song from the beginning:
Now find the start of the solo. To skip ahead, use the -k option to skip frames. Try at about 1000.
mpg123 -k 1000 runaround.mp3
Now use a binary search: If you hear the solo playing, go backwards, if you don’t go forwards. At 1000 I hear it playing, so I go back to 500, then 250. At 250 I just hear the intro guitar, so I jump forward by 125 to 325 and so on until I figure out that the solo starts roughly at 270. Now I slow down the playing by half:
mpg123 -h2 -k 1000 runaround.mp3
It is distorted as all hell, but I can make out the notes, and more importantly, match it on a piano, harmonica or saxophone. I can slow it down even further with
mpg123 -h3 -k 1000 runaround.mp3
Which is as far as I would want to go. Note that for older recordings, where the solo may be exclusively on the left or right track, you could add the -0 or -1 options to shut out more of the background noise.
As you progress, you want to move forward in the song. Use the -v option to display frame information as you play.