Humming is a ubiquitous and mundane act many of us perform. The fact that we often hum to ourselves, to family members, or to close friends suggests that humming is a personal, intimate act. It can also be a powerful way in which people open up to others and share collective memories. In religious settings such as Tibetan chanting, humming offers a mesmerising sonic experience. Then there are hums that resound regardless of human activity, such...