Jim Cole & Spectral Voices' music features harmonic overtone singing:  each person sings two or more notes at once (aka throat singing).  They have used a water tower and other spaces as musical instruments, within which to create mesmerizing music. 

Spectral Voices' music has been described as mystical, wondrous, achingly poignant, contemplative, ethereal, relaxing, transcendent, hypnotic, powerful, primal, soothing, intense, meditative and sublime...