Composing music from algorithms

Reed Kastner isn't your typical music composer sitting at a piano with pen and paper waiting for inspiration. Instead Kastner, a member of The Citadel Honors Program, used an algorithm, a computer, and a background rich in math and engineering to create music.


"This project allowed me to apply the field of electrical and computer engineering to my interest in music. It was very pleasing to see a computer compose music that actually sounded musical," said Kastner.

The algorithm Kastner used was developed by Citadel Electrical Engineering professor Maj. Thomas Jerse using fractional noise. The actual sounds heard in the composition were not noise, such as you would hear from a radio tuned to a station off the air. Instead, the noise-generating algorithm produced a series of numbers used to select the sequence of pitches for the composition that could be then played on a musical instrument.


At one end of the fractional noise spectrum is white noise or randomly generated tones with no pattern. On the other end of the spectrum is brownian noise, which has a pattern that meanders up and down a musical scale. Studies show that pink noise, which falls somewhere between white and brownian noise, is closer to the spectrum of man-made musical compositions in a variety of styles.

The unique algorithm used has a numerical control that enables the noise to be varied smoothly from one type of noise to another. Kastner took the algorithm created by Jerse and put it into a loop, a cyclical computer program, which then generated a string of numbers based on its noise output. Then he assigned the computer-generated numbers a musical pitch to come up with his music.The numerical control on the type of noise was varied to obtain different kinds of compositions.

"Reed was able to apply the algorithm in creative ways and came up with a method to combine multiple sequences that produced reasonable harmonies," said Jerse. The project served as Kastner's senior Honors project.

The Honors Program is a specially designed educational experience meeting the needs of students with an outstanding record of academic achievement and a sense of intellectual adventure. It was founded in 1987 by Col. Jack Rhodes, who is currently the program director. Kastner, who graduated May 10, received an Air Force commission and is scheduled to begin navigator training at the Naval Air Station Pensacola, Fla., in November.