“Look,” says tabla virtuoso Pandit Tanmoy Bose, slowly moving his index finger along the rim of a half-filled glass of water, “listen to what happens”. I prick up my ears, and a piercing, whistling sound rings out. I’m flabbergasted—it seems almost magical, and when I try my fingers at it, I fail miserably. Pandit Bose bursts out laughing. “You need to practise a bit!” he says, adding, “Do it at the right frequency, and that glass will shatter.”