“Theories vary as to why it works. One is that it doesn’t fit with antisocial youths’ perception of cool; another that teenagers can hear high-frequency overtones that adults can’t detect, which upset them (though music students of a similar age are evidently immune). As for the rest of us, when TfL did a survey of 700 commuters, ‘they overwhelmingly agreed that hearing classical music made them feel happy, less stressed and relaxed’.”