If you think about it, musical instruments provide really intriguing examples of user interface design. While it can take years of training and no small amount of aptitude, an instrument in the right hands can provide highly nuanced control over the many aspects of sound that come together to form one of the highest forms of human expression. And even for those of us who will never achieve such virtuosity, merely using such a “user interface” can result in a great sense of enjoyment, immersion, and fulfillment (what is often referred to as a state of “flow”)…