You are lying in bed on a quiet night when a persistent droning vibration creeps in, like a diesel engine idling outside your window. You wake your partner, but they hear nothing. The street is empty, yet the noise vibrates through the mattress and into your bones.

This deep dive investigates the Hum, a low-frequency noise reported worldwide that only about 2 percent of the population in affected areas can hear. We explore the mechanics at the intersection of human biology, heavy industry, psychology, and physics, asking whether the Hum is a byproduct of our mechanized world, a natural anomaly, or something built inside the human auditory system. With the phenomenon linked to ruined lives and at least three suicides in the UK, the stakes for sufferers are profound.

• The Taos Hum was mapped peaking between 30 and 80 Hertz, in the e ...