What Is Polyphonic Singing And Is It Even Possible?

Last year around this time we shared a video with you of Lalah Hathaway who seemed to have the miraculous ability to sing harmony with herself in real-time. We thought she was a freak of nature, but it appears that there are others. Turns out that this teachable technique is  known as 'polyphonic singing', and here's vocalist, Anna-Maria Hefele demonstrating the ability...