noise study – structure

In James Tenney’s “Computer Music Experiences” article, he presents the following chart:

CME Fig 3.tifFrom this we can see 3 parameters, “note duration”, “intensity” and “bandwidth”. The subsequent values “mean pitch level” and “pitch range” are determined from the “bandwidth” profile. The charts that Tenney gives for “mean pitch levels” and “pitch range” don’t seem terribly useful at first glance (pitch level of “1” and pitch range of “5”?). However, looking at Matthew’s Music III paper, I see that pitch is specified in octaves, so that Middle C is 3.0. It looks very much like all of the 5 voices started with a mean of C1, C2, C3, C4 and C5. What isn’t completely clear is whether the center of the note varied, or if the bandwidth simply was controlled by the noise intensity alone. The intensity is certainly using the Music III CVT01 function, which used decibels. CVT01 = 10^P3/20.0, which means the amplitudes vary from 1.0 (0) to 501 (54).

In the instrument, there is a noise frequency and amplitude input, each of which can vary or remain constant. There is also the oscillator frequency input, which can also vary (by linear change) or remain constant. Tenney mentions that “for center frequency, the toss of a coin was used to determine whether the initial and final values for a given note were to be the same or different”. From listening to the piece, it seems that the other parameters (noise frequency and amplitude) were generated in a similar fashion.