The Apprentice Who Learned to Hear the Beats

In 1987, a sixteen-year-old named Marcus Chen began apprenticing under piano tuner Walter Kraus in Portland, Oregon. Walter would strike two notes simultaneously and ask, "Do you hear the beats?" Marcus heard only sound — clear, unremarkable sound. Walter shook his head gently and struck the keys again. "Listen deeper. There is a pulse hiding inside the note." For weeks, Marcus heard nothing.…