this is absolutely amazing : http://www.radiolab.org/blogs/radiolab-blog/2011/jul/26/4-track-mind/
also, lest anyone misunderstand what the hell is going on in this guys' head, Jad explains it in a comment to an idiot on the message board : Jad
Bob's abilities don't seem to be linked to any easily identifiable form of synesthesia.
When Bob hears music, he doesn't have the triggering of colors or smells that's typical of classic syntesthetes. But he does say he has intense emotional responses to different notes and cords. So certainly there may be some kind of unusual crosstalk between his emotional mind and his musical mind (to whatever degree they're separate).
To those folks who question just how extraordinary Bob's abilities are to begin with, perhaps we didn't do our job well enough.
Think of this way: Each of the four symphonies is in a different key and at a different tempo. And within each, the musicians are constantly modulating keys and the conductor is speeding up and slowing down the tempo for dramatic effect. So you've got four very complicated pieces of music with independently fluctuating melodies, keys and tempos...and all four start at different times. So there is nothing between them that's in sync.
Yes, Brubek's drummer Joe Morello can play separate rhythms with each limb, but he's still moving all his arms and legs to ONE beat, ONE tempo. Now, if Joe could somehow decouple his four limbs and simultaneously play chopsticks on the marimba at 122 bpm with his left arm while juggling three oranges at precisely 89 rpm with his right arm while tapping out the Gettysburg address in morris code at the speed of one word per second with his left leg while spinning a basketball on the big toe of his right foot...then you'd have something approximating what Bob Milne seems to be doing in his head. In my opinion.
Thanks everyone for listening and commenting!