Four sine waves tuned to a major seventh chord in Pythagorean intonation then shifted through twelve linear temperament scales (built on ratios of 3/2, 9/8, 27/16, 81/64, 243/128, 729/512, 2187/2048, 6561/4096, 32/27, 16/9, and 4/3).
Created with Audiomulch.
For a long time, I'd wanted to make a piece out of sine tones. Then I went to a music lecture where the speaker described hearing an Indian singer sing a note that took 30 seconds to slide one semitone in pitch. Haunted Comma came quickly from combining these two thoughts.
A Pythagorean scale is made by taking the tuning ratio of 3/2 (i.e. a perfect fifth) and stacking it up, one on top of another, dropping down an octave when necessary, until a full scale of pitches has been created. Other linear scales can be built in the same way, using a different ratio. Haunted Comma begins with a major seventh chord tuned to the Pythagorean scale, then retunes itself to the same chord in different linear scales. Each successive scale is made from stacking the next interval in the Pythagorean scale. It takes two minutes for each tone to slide from its tuning in one scale to the next. There is a brief period of stability upon arrival at each new scale, before the sliding resumes.