Flowing Wall of Glissandos

~ A 2-Stage Sound Design Illustration ~

prepared by A Endrich

from a passage in Crossing the Dark Rift

Goal: a descending, vibrating, flowing
wall of thin streams

Stage 1: prepare a thin, descending, vibrating filament

Source: a single stroke on a Tibetan singing bowl bellae.wav (4.9 sec).

The first step is to soften the attack and make the ending of the sound more gradual. This is done with DOVETAIL, with 1 sec. of exponential curve (the rate of amplitude increase accelerates) at the beginning, and 1 second of linear slope (steady rate of decrease) at the end. The output is named bdtG5.wav.

The next step is to make it more supple by giving it a slow oscillation, moving between harmonic and inharmonic states – using STRANGE WAVER, we hear it get a bit tighter and thinner as it goes up. The rate of oscillation is 4 x per second (0.25), but a timestretch factor of 5 slows this down considerably. The lowest frequency affected is 50 Hz: bdtG5wavr.mp3.

Now we need to make this sound longer, so TIMESTRETCH the sound by a factor of times 2.3: bdtG5wavrstrx2&3.mp3. It is now 11 seconds long, and we have a nice long wavy filament.

The descending glissando aspect is achieved with STRANGE SHIFT, with which we push the sound upwards by 3000 Hz and have it gradually drop back down to its original frequency level over its 11 second duration. This uses a time value breakpoint file for the shift_factor:

 0	3000
11	   5
Now the filament is a long, thin descending glissando: bdtG5wavrstrx2&3ss.mp3

The desire to have the sound 'vibrate' leads us to further enhance this sound with a time-varying vibrato. So we start off with 1 vibrato per second and end with 30 per second. This information is provided in another breakpoint file for the vibrato_factor:

 0	  1
11	 30
This is the result: bdtG5wavrstrx2&3ssvib.mp3. This final enhancement is judged to provide a sufficient basis for creating a flowing wall/curtain/veil of these filaments, so we move on to Stage 2.

Stage 2: create a flowing, vibrating wall of glissandos

The plan is to use TEXTURE SIMPLE, mode 3 to pack these filaments closer together: 0.1 sec apart, with a 0.05 timing offset. The richness of the texture is further improved by providing a 3-pitch harmonic set: D-F-G. This means that each of the note events, spaced at ca. 1/10th of a second, will be randomly placed on either D, F or G above Middle C. At such a close temporal spacing, this means that there will be a 3-note chord of descending glissandos.

Now we have reached our goal of a descending, vibrating wall of sound: tz5s2tex3.mp3, used for the 2nd section of the 5th Tzolkin cycle.

Last updated: 27 September 2003
mp3 format changes: 21 February 2010 (sources or near sources are kept as wav)

©2003-2010 Archer Endrich Chippenham, Wiltshire  England, both texts and music. All rights reserved.