Think about playing piano for a moment. By developing eye-hand coordination,an intelligent deaf mute could learn to play Bach. With practice,you can read the music and push the right keys;you can press the right keys and write down the music.
Now,consider developing eye-hand-ear coordination. When you manipulate your fingers(hands),you can hear the notes and write the music. When you see the music,you can press the keys and hear the sounds in your head. When you hear the notes in you head,you can see the notes in your mind and know which fingers to push.
Glenn Gould used to drive his sound engineers nuts because he sang along with his playing-his ears were connected to his hands and eyes. The connections were communitave,in a mathmatical sense.
My point? The original cd s are closer to what Gould actually recorded-humming and all. Gould was one of the outstanding Bach players of the 20th century and we are fortunate to have his recordings-warts and all.
In addition to his Goldburg Variations(both versions-I prefer the '55s even if it's an antiquated recording),his French Suites and English Suites are great.