By Wojciech Mikoluszko, a science reporter from Poland. Mikoluszko is currently a Knight Science Journalism fellow at MIT. [host introduction] You could hardly find a bigger contrast: the clean voice of a cello breaking through the dirty noise of a subway. And this is what people hear in Cambridge subway stations. Many passengers stop, are moved, laugh and even miss their trains listening to the music. But why do professional musicians do this? Producer, Voytek Mikoluszko, dug into this question. He reports from KSJ in Cambridge.