Some residents and visitors in the small city of Taos, New Mexico, have for years been annoyed and puzzled by a mysterious and faint low-frequency hum in the desert air. Oddly, only about 2 percent of Taos residents report hearing the sound. Some believe it is caused by unusual acoustics; others suspect mass hysteria or some secret, sinister purpose. Whether described as a whir, hum, or buzz and whether psychological, natural, or supernatural no one has yet been able to locate the sound's origin.