We listen to music with our ears, but also our eyes, watching with appreciation as the pianist’s fingers fly over the keys and the violinist’s bow rocks across the ridge of strings. When the ear fails to tell two instruments apart, the eye often pitches in by matching each musician’s movements to the beat of each part. A new artificial intelligence tool developed by the MIT-IBM Watson AI Lab leverages the virtual eyes and ears of a computer to separate similar sounds that are tricky even for humans to differentiate. The tool…