Spectral content as a structuring process

In order to situate acousmatic pitch and intervallic pitch constructs as structuring processes this section begins with a review of sound spectra, the foundation for pitch.

As explained in 2.3, sound spectra can be seen to exist on a double continuum. The continuum on the y-axis addresses the tactility factor, the internal microstructure of sound spectra, which can range from smooth to granular, and which I consider as a basis for describing the type of ‘materiality’ perceived in a sound. The continuum on the x-axis addresses spectral content from the perspective of harmonicity or noise. On the one extreme is noise, on the other extreme are harmonic spectra that are based on the harmonic series, and in the middle lie diverse types of inharmonic spectra. The surprising fact is that inharmonic spectra and noise can enhance and steer the structuring capacities of pitch and intervallic pitch constructs, and vice versa (pitch and intervallic pitch constructs can enhance and steer the structuring capacities of inharmonicity and noise.)

Acousmatic pitch and intervallic pitch constructs

As discussed in 2.3.2, the term acousmatic pitch refers to a perceptual construction based on harmonic sound spectra. We also know that the range of possibilities for eliciting pitch in acousmatic music can be extended, poietically, through degrees of harmonicity in sound spectra, which, in turn, can affect, esthesically, the type of pitch construct listeners might construe according to their perspective. In this way, pitch can operate as a flexible percept. This is because perceived pitch can play a significant role in the spectral identity of a sound-shape as conveyed not only through varying degrees of harmonicity, but also through the relationship these spectral components have, as a whole, when they co-exist with inharmonic or noise-based spectral components in a sound. Acousmatic pitch thus can be a perception of real or local pitch or a gradation of pitch-noise.

On an initial level, we know that pitch can contribute to a sound whose shape is based on natural energy models (e.g. percussion resonance, friction, fluidity, rotation, rebound), and the way it evolves and changes. Further, we also know that in acousmatic music harmonic spectra are not necessarily dominant. Rather, threading harmonic spectral components into a spectromorphology can convey pitch and harmony to varying degrees. These pitch elements can disperse, converge, overtake

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other spectra, or recede. Additionally, harmonic spectra can outline, highlight, root, or suspend essentially inharmonic and noise-based sounding gestures.

Inharmonic and noise-based spectra can cohabit with pitched spectra in a sound-shape, and, therefore, unfold and flourish in an environment where they mutually contribute to the expressive aspect of that sound-shape and to each other.

Indeed, the existence of pitched, inharmonic and noise-based elements in a sound-shape, and the way they can develop together over time can be very sensual. Pitch becomes liberated from a definition and function centred on the sounding possibilities provided by traditional instrumental and vocal sound. The existence of inharmonicity and noise can contribute to a perceived importance of pitch a context where inharmonicity and noise are more dominant. Further, if pitch is conveyed through an unusual sound-shape it extends the possible gestural forms in which pitch can be expressed. This means that pitch and harmony can function in new ways, and accrue new meanings.

Inharmonicity and noise

As discussed in 2.3, not all internal frequency components in inharmonic spectra have a mathematical relationship to a fundamental frequency, though individual frequencies can be periodic. Hence, inharmonicity can be seen as a question of degree. Further, as discussed in 2.3, noise comprises all audible frequencies, involves random changes in frequency and amplitude, and has constant energy per unit bandwidth that is independent of the central frequency of the band (Van Nostrand, 1968: 1197).

Inharmonic and noise-based spectra have a structural role and add a sensual and poignant aspect to the work. This is due to two factors: (1) the tactility factor of inharmonic and noise-based spectra which is frequently granular, a quality that can seem to render the sound-shape like a material object and therefore, accessible to touch;

and (2) the inclusion of noise and inharmonic spectral components with harmonic spectral components in an acousmatic work which, as noted, can highlight the perceived importance of pitch by way of comparison. They extend the possibility of expressivity. Only through the combined forces of harmonic, inharmonic and noise-based spectra can music attain its true expressive potential. I shall now examine the relationship between perceived acousmatic pitch, harmony, inharmonicity and noise, and acousmatic form in parts of selected works in the composition folio.

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Selected works in the folio from the perspective of spectral content (i) Ether

In Ether, intervallic relationships serve as a skeletal structure for the first 6’ of the piece. However, the pitches involved are often separated by an octave or more, which disengages the sense of pitch centre and the perception of traditional intervallic relationships. In this way, inharmonic and noise-based spectra are not subsumed in harmonic spectra. Instead, harmonic relationships are developed, re-iterated and/or sustained through klangfarbenmelodie, sound material that often has a similar pitch but different timbre, a technique that disassociates pitch from a specific timbre and allows for greater compositional freedom. Further, pitch is often conveyed through varying degrees of inharmonicity. Finally, in contrast to the fixed quality of harmonic spectra, the inharmonic and noise-based spectra seem to elude a ‘gravitational pull’ towards a harmonic resolution more easily and ‘pass through’ the dense spectral mass inherent in other sound shapes. An example of this type of spectral structuring process can be apprehended in the passage in Ether, from 2’30” to 5’18” (sound example 3.26, track 72), where pitch is conveyed through harmonic spectra and varying degrees of inharmonicity. For example, at 2’45” a pitched (G#4) quasi-vocal ethereal sound, like

‘pitched, human breathing’, which is rhythmically articulated with a rapid stringed instrument type of bowing, appears on channels 7 and 8 and occasionally on channels 1 and 2.¹²⁴ This sound-shape continues until 3’52” with different levels of intensity. It is underpinned by a timbrally rich, brassy, pitched sound (F 3) at 2’46” on channels 3 and 4. At 2’49” a percussion resonance (G3) can be heard, albeit briefly, on channels 7 and 8. The percussive attack followed by an upward glissando that begins the piece reappears at 3’52” on channels 5 and 6 (A3). However, in this third instance, the sound-shape does not glissando up to an E4 but to a D4. The ‘pitched, human breathing’ sound, noted at the beginning of the sound example, returns briefly at 3’46”

in channels 3 and 4, and a soft, pitched (G4) sustained sound is briefly heard in channels 5 and 6 from 4’11” to 4’19”. At 4’24” the reversed part of a metallic resonance (G flat 3) can be heard on channels 5 and 6. At 5’02” the attack part of the percussion resonance occurs on channels 5 and 6. A very high-pitched sustained sound (D 6) can be heard throughout part of the section, 4’05” – 5’18” on channels 1 and 4, where it can be apprehended as a spectral canopy.

124 Several sounds in this section appear at the beginning of Ether, the first minute of which is analysed in Chapter 6 from a spatial perspective. As discussed in Chapter 6, the spatial organisation at the beginning of Ether is based on a double spiral which is conveyed through loudspeakers placed in a setup that can be described as a cruciform overlaid with a square (see Figure 6-7). However, after the second minute of the piece the double spiral slowly gives way to spatial organisation through stereo pairing, albeit as conveyed through the unusual loudspeaker setup.

117 (ii) Les Forges de l’Invisible

In Les Forges de l’Invisible inharmonic and noise-based spectra are frequently embedded in sounds containing harmonic spectral components, allowing relationships to occur between harmonic spectra that could not otherwise exist. For example, instances of simultaneous harmonic spectra are vitalised by virtue of the connectivity and diversity offered by various degrees of inharmonic and noise-based spectra.

Additionally, relationships between various registers of inharmonicity and noise are enhanced through harmonic spectra. This is because, within my works and particularly in Les Forges de l’Invisible, the relationships harmonic spectra have with other harmonic spectra are often conditioned and qualified by the types of inharmonic and noise spectra in the same topology and vice versa. For example, different degrees of inharmonicity help to separate sounds that occupy identical, similar, or contiguous pitch spaces in the second movement of Les Forges de l’Invisible. Additionally inharmonicity can appear to engender pitch motion, and it can serve to bind spectral space in instances where a harmonic topology can, otherwise, seem spread out.