Infrasound Anomaly
The Bristol Hum
Bristol, England, UK — first reported 1979
~40 Hz
A drone-like hum that has plagued residents since the late 1970s. Louder at night, indoors, and in rural areas. Some describe it as pulsating; others as steady.
Theories
- Industrial ventilation systems
- Tidal bore resonance from the Severn Estuary
- Underground water infrastructure
- Atmospheric temperature inversions trapping sound