____ _ . . . . . . . ……Lines, Ramps, Anti-Particles

I was going to start this article with the title “Line, Point, Space” yet the starting graphic seemed more appropriate. I come from architectural drawing and visual design disciplines and as a result I tend to visualize audio composition, especially microsonic composition, in terms of lines, points and spaces.

I see two approaches to the direct synthesis of microsound.

The additive, in which, a unit of microsound (µu) is added with/or after another to create a striated or continuous aural entity.

…......Point, line, cloud

The second strategy I call subtractive. The line is robbed of its continuity, striated into either a µu or a microtemporal unit of space/silence (-µu).

____Line, point/space

Microsilence is a finite, concrete unit, an brief aural emptiness, such as negative space in architectural ground theory.

The dispersion of sound particles creates spaces between them, -µu . They are apparent to the listener, who can hear them , though they can’t hear them, they make up the negative aural space, implied time.

The trivial wave, the line is a monotonous restrictive phenomena, an unchanging irritating aural continuity. One that in order to hold the listeners interest, must be at least modulated and/or at best fragmented and dispersed to new locations on the plane.

We catch one, maybe two brief moments of the line before we loose interest.

the ~u and the µu exist on either side of the boundary of microtemporal aural perception (Roads, 2001).

The Flutter Region

Unlike classic wave synthesis, microsonic techniques exhibit a unique characteristic in that when µu is repeated at up to the limits of sub-audio rates (<~ 10-40Hz) the listener perceives the primary acoustic signature of the process, that is, the microsound.

As this unit is repeated above this rate, the listener begins to resolve the discrete units into a continuous event. The exact threshold of discrimination depends on the duration and timbre of µu, but somewhere in between exists a subjective transitional boundary which, for convenience sake I refer to as the flutter region ( µƒ ).

An example of crossing µƒ, is Mälarsæng (Clarke, 1987). Belcanto vocalisations octaviate into droplets and then into chimes. The listener’s perceptual reference is shifted seamlessly from one sound object, the voice, to another, the chime, which seems to have emerged from the depths of the former, creating a psycho-acoustic narrative.

The neurological limits imposed by forward masking (Roads, 2001) permits microsound to create powerful narratives and to play with the listener’s expectation between the continuous and striated contents on the aural plane.

The Elementary Signal Engine

In formant based particle synthesis two classic methods have been employed to populate this plane. Octaviation in FOF synthesis (Rodet, 1984) and Pulse masking in Pulsar synthesis (Roads, 2001). Both are techniques which permit the user to play with the listener’s psycho-acoustic expectations by creatively crossing µƒ.

The original conception of FOF was to create tones similar to those of the human singing voice. Through octaviation the user can cross below µƒ as to perceptually separate FOF particles.

FOF tones are constructed through several layers of periodic emissions which when summed create the fundamental frequency.

These layers can be consecutively faded in and out thus dropping/raising the fundamental by an octave. The result is that listeners perceive vocaloids as changing gender. The technique, however, is limited to a predetermined numbers of layers, thus restricting the variety of particle groupings.

Pulse masking in Pulsar synthesis (Roads, 2000) differs in that it permits whole number groups of pulsarets to be switched on or off using a variety of grouping strategies.