In 1969, American composer James Tenney wrote For Ann (rising), one of the “earliest applications of gestalt theory and cognitive science to music.” (source: wikipedia). The auditory illusion heard in the piece is achieved by layering multiple rising sine waves.
Tom Erbe recent wrote a blog post, Some notes on For Ann (rising), in which he describes in detail the specifications of the piece. This includes a thorough description, an excerpt of Csound code, and a PD patch he recently created. The PD patch is available for download at his site.
I myself love studying classic computer music languages and instrument designs, so this afforded me the perfect opportunity to study the piece. For Ann (rising) is also a personal favorite of mine.
First, I assembled the Csound version based on Erbe’s notes and Csound code excerpt, which was a straight forward process. I copied the instrument without any modifications. Then I generated the score with the following two lines of Python code:
for i in range(0, 240): print 'i 1 ' + str(i * 2.8) + ' 33.6'
The Csound csd is available for download here.
The next thing I did was realize the piece in SuperCollider based on Erbe’s Csound code. The technical simplicity of the instrument as well as the process for spawning voices allows for the piece to be expressed in less than 140 characters when translated into SuperCollider, making the following line of code twitter ready:
You can view the tweet here.
I want to thank Tom Erbe for publicly sharing his work and insight, which has allowed this classical computer music piece to be reconstructed in multiple modern day mediums.