2 overtone singers in the water tower:

Searching for ever more reverberant spaces eventually led Jim Cole to an enormous empty water tower. The 120-foot-tall water tower was an ideal space in which to develop Spectral Voices' unique towerovertone singing music.  Imagine the setting:  Looking up at the modern-day megalith looming above, you're surrounded by sights and sounds of the natural world: trees, birds, wind and rustling leaves.  Using a  pipe wrench, you loosen two large bolts to swing open the oval hatch near the base of the water tower.  You crawl through the opening in the steel wall and emerge into a vastly different world of total darkness and long reverberation.  The sensation is akin to diving deep below the surface of water and realizing you're in a whole new slow-motion world.  The senses are heightened.  A flickering candle casts dancing shadows on the curved wall of the water tower, evoking images of some ancient cave.  Every sound lasts 20-30 seconds, making speech barely intelligible.  But music, when it is slow and spacious, is exquisite.

 3 overtone singers in the water tower:

Singing in this extremely reverberant environment, Spectral Voices learned to use the water tower as an instrument, continuing to develop overtone singing and adapting ideas to the acoustics of their surroundings.  An amazingly long decay time contributed greatly to the depth and richness of sound.  The huge reverberation made it possible for a single voice to build complex chords simply by singing several pitches in succession.  A series of notes would hang in the air, turning melodies into chords.  The resonant acoustics inside the water tower reinforced even the quietest sounds.  Overtone singing long notes with very long reverberation creates music that lingers in space and in the mind.  The experience is very peaceful;  time seems to stand still.

Three small holes in the ceiling allowed sounds of nature to enter: in the background of many tracks on Spectral Voices' recordings CoalescenceSky, and Innertones, one can hear birds calling, the wind blowing, and rain falling outside the water tower and echoing within.