Although I have listened some songs hundred of times I can't sing the lyrics to any of these songs from beginning to end without pauses. However I am able to whistle the whole song without difficulty.
I also find that when I take the supplement piracetam, my ability improves. (It has in fact improved over time anyway)
Piracetam has something to do with interhemispheric communication.
Any answers for what causes this condition?