Petroglyph Music (Label) says:
Theo Calis: sounds & rhythms, mix, mastering
Martin Hoogeboom: strategies & assemblage, additional sounds
Inspired by the works of painter Agnes Martin.
Voice of Agnes Martin taken from an interview done by Chuck Smith & Sono Kuwayama
at her studio in Taos in November 1997. (https://vimeo.com/7127385)
Rutger Muller public domain sounds on The Grid: Red Bird
Singing voice on The Grid: Red Bird by Kathleen Ferrier ('O Come All Ye Faithful'
recorded August 6th 1948)