The Physics of ... Singing

Singing came naturally to the opera mezzo-soprano Marilyn Horne, who made her public debut at a town picnic at age four. Her granddaughter Daisy, now just ten months old, appears to be even more precocious. "When I picked her up the other day, I swear I heard her begin to hum," says Horne. "To test it out, I came in on harmony--and she held her pitch. My daughter heard us and nearly passed out."