A Denver audiologist said that she had recorded a steady vibration of 17 cycles per second with a harmonic rising to 70 cycles per second near Taos. The low range of human hearing is 20 to 30 cycles per second. Some residents of Taos are plagued by this machine-like sound that grinds away 24 hours a day, with only occasional respites. Most people, however, cannot hear the hum at all. Nevertheless, it is there.
Instruments pick it up.
In fact, they have even recorded a higher-frequency component that pulses between 125 and 300 cycles per second. The cause of the hum is a mystery. One hint comes from the observation that the hum seems concentrated along the Rio Grande Rift, a fault that also runs into Texas and Colorado. The world is full of mysterious hums. Ordering information here .