PULSAR SYNTHESIS: WHAT IT IS AND WHY I EMPLOYED IT
In designing sound behaviours, I took into account the large amount of parameters that we wanted to sonify, and the fact that often molecular quantities are understood in terms of particles. I therefore adopted a form of synthesis called pulsar synthesis. Pulsar synthesis is often referred to as ‘nonstandard’ synthesis due to its degree of difference from forms of synthesis traditionally associated with analogue synthesis (Roads, 2021b). It is endemically digital in its approach to synthesizing sound in that it applies a shaping envelope to a single duty cycle of an already shaped waveform, resulting in a modulation in the microsound domain (Roads, 2021a).
I mapped data concerning colour, degree of translucency, and chemical composition to sound parameters within the pulsar synthesis for Pure Data (Pd, 2023) objects developed by Rodney Duplessis (Duplessis, 2023). I customised Duplessis’ design through the addition of inlets for dataset control of envelope and waveform. Duplessis’ implementation and Pd more CPU intensive than other options, for example, Supercollider, might have been. However, in the present iteration of this project, I require only a small number of pulsars. Taking this project further, I intend to experiment with the New Pulsar Generator (nuPG) developed by Marcin Pietruszewski in Supercollider (Pietruszewski, 2023). In this environment, unit generators may be instantiated and deactivated dynamically whereas in Pd, for the most part, objects required must exist whether in use or not, and therefore consume CPU cycles even when not in use. However, for the present work, immediate familiarity with the Pd platform proved expedient.
DESIGN AND MAPPING BETWEEN SOUNDS AND MOLECULES
Ten molecules were sonified using two pulsar generators each. The molecules chosen represent the most abundant chemical components in the glass specimens in question. These are the oxides SiO2, Na2O, CaO, Al2O3, K2O, MgO, Fe2O3, MnO, TiO2, and P2O5. Notably, the signature elements that flag whether glass recycling has occurred is found in the less abundant category of trace elements, not included in this first venture, but to be included in subsequent work as this is central to Dr. Bertini’s research.
Each molecular component received a binary ‘stereo-like’ presentation: two identical pulsars were spatialised to opposite sides of the spatial field, to create a sense of connectivity between them. When these were further subjected to movement or re-arrangement, the binary pair remained opposite one another, as opposing magnetic poles. In pulsar synthesis, each pulsar generator applies pulsaret and pulsar single-period waveforms to create an overall envelope applied to an impulse of sound, which in the case of my models resulted in twenty pulsar generators with forty waveforms being processed at a given moment. The impulses generated are then sequenced in a designed series of sounds and gaps, and these produce the tone colour heard, whose overall waveform results in sound correspondingly rich in harmonics. Many sounds generated through pulsar synthesis have a robust visceral, almost tactile quality. The pulse trains in this work were designed with reference to the number of connections between atoms in the molecular lattice of each molecule in question.
