Examples taken from the acousmatic music repertoire will now be discussed in order to illustrate how aspects of spectromorphology, contour, source association, gist and streaming are significant to the perception and discussion of sound identities.
23 Brief time slices of the auditory signal might be sufficient to determine the gist of the auditory scene, and activate possible templates. As more information is accumulated over time the number of possible templates is reduced, and attention can then focus on confirming the appropriateness of the template and/or to learn about the source. Naturally, unfamiliar sounds will be identified less easily. This whole process should be continual and would be expected to occur in parallel with more detailed processing within the focus of attention (Harding, Cooke et al. 2007, 411).
2.4.1. Extract from Novars by Francis Dhomont
The opening of Dhomont’s Novars (1989) features attack-decay morphologies in a variety of orientations (audio ex. 1_1, 0’00 – 1’05). 24 A variety of forward and reverse versions exhibit different kinds of prolongation while also creating occasional upbeats;
distinct sound shapes are easily discernible. The identities of the weakly source-bonded opening instances are defined and united by gestural impetus, morphological profile, and a pitch content that is primarily stable. Pitch stability lends the passage a sense of permanence, yet the attack-decay morphologies also exhibit spectral contours, which manifest as progressive high-frequency restriction or sudden spectral
brightening. All these features contribute to the gist of these identities. Lewis has described these as “Filter-Swept Chords/Resonances” in his analysis of this work (1998, 69), and the occasionally unexpected nature of the ‘filter-sweeps’ further
characterise the identity. 25 High-frequency restriction often coincides with the decay of the sound, as might be expected in real-world decay phenomena (although here it is exaggerated), but occasionally the reverse-attack morphologies feature similar
progressive high-frequency restriction. This subverts any sense of realism and further characterises the sound material. According to Smalley’s (1997) concepts of gestural surrogacy, these identities can be considered third-order, tending to remote, gestural
surrogates 26; listening tends to focus on the sudden gestural action, and how the spectra progress over time in both predictable and less predictable ways.
24 Timings in parentheses indicate the location of that example within the work.
25 Lewis further asserts that the pitch structure of the resonant sounds is based on “a quasi-fundamental, above which float other ‘partials’ based on a modal arrangement” and that, on occasion, this harmonic pitch set is disturbed by resonances foreign to the modal scheme (1998, 69).
26 Smalley suggests that sound-making gestures (whether of human, animal or environmental origin) can be seen to create spectromorphologies. Conversely, any perceived
spectromorphologies may be indicative of specific gestural events, which are identifiable to varying degrees of accuracy. Thus, the degree of perceived connection between a
spectromorphology and its gestural origin can be described in terms of its gestural surrogacy.
The categories are: first-order surrogacy (sound-making prior to musical organisation); second-order surrogacy (traditional instrumental play/performance practice); third-second-order surrogacy (imagined gestures and questionable reality of the source or cause); and remote surrogacy (source and cause are unknown, and human gestural origin is absent) (Smalley 1997, 111-112).
The linear arrangement of the attack-decay morphologies, combined with the subtle changes in spectral content, focuses attention on the progression from one instance to another. The strength of identity of this sound material is reinforced by its temporal organisation, and the play on permanence (pitch) and variation (gesturally and spectrally) is a significant aspect of the passage. There is an intrinsic connection among forward-attack and reverse-attack morphological types (a form of ‘source bonding’), their arrangement here suggesting an organisational process evolving from the opening attack morphology. This, coupled with the general pitch stability, creates a sense of cohesion within the sound world. Indeed, a sense of cause-and-effect exists between each attack-decay structure, and the sound material can be viewed as a series of morphological events that contribute to the perception of a longer, composite identity.
2.4.2. Extract from Crystal Music by Stéphane Roy
In Roy’s Crystal Music (1994), the spectromorphological characteristics of certain identities allude to a variety of source materials including those of possible membrane (could be skin, plastic or rubber), ceramic, metallic and electronic origins (audio ex.
1_2, 6’04–6’46). For example, the short resonant decays of the iterations, consisting of high register and noise elements, contribute to the suggestion of a membrane source. A further characterising feature of the membrane-like sounds is the gradually descending spectral contour of each group of iterations; this can be heard throughout the extract and serves to bond those identity types to each other. In general, while the exact sources are not discernible, there is a strong sense of material identity and allusion due the supposed frictional causal activity and re-iterated multiple attacks, giving clues to the nature of the source material and its gestural causation. Indeed, there is an
impression of intense physical activity associated with the manipulation of the supposed sound sources.
This extract also exemplifies simultaneous identity streams. Medium-high pitch impulses, of inharmonic/metallic spectral character, and featuring prolongation by a short ‘delay’ effect, create one stream existing in the foreground of attention. The reiterated membrane-like sounds create another stream, which could be seen to divide subtly into further sub-streams based on distinctions in supposed gestural causation (e.g. rubbing or slower, rhythmical impacts), and the division into higher and lower registers. Perceptual grouping is likely to occur based on these sound-type distinctions, the membrane-like entities becoming a characteristic feature of the acousmatic image.
Some of the emerging artificial/synthesised identities possess similar spectral qualities to these membrane instances (such as pitch/noise complexes with medium- to high-frequency emphasis), while their morphological profiles (short, iterative impulses) allude to similar friction-based activity. As a result, while initially of a distinct stream or identity, they might gradually become perceptually grouped with the membrane sounds.
The spectromorphologies in this example do not possess as distinguishable a shape when compared to those found in the Novars extract. The resulting acousmatic image is built from a wider variety of sounds and is energetically more volatile. The rate of change between the constituent sounds creates a more complex sound world, encouraging listening to shift continually among the identity streams, enhancing the music’s sense of volatility. This example illustrates a situation in which no single instance among the membrane-like sounds has a marked significance of its own, but rather the overall textural impression characterises the sound identity. This type of sound identity may be subject to non-unit-based recurrences based on common textural characteristics.
2.4.3. Extract from Stéphane Roy’s Trois petites histoires concrètes
Perceptual streams may also be formed when identities are not initially heard simultaneously. In Ruptures, the first movement of Stéphane Roy’s Trois petites histoires
concrètes (1998), the sustaining pitched material that occurs from the outset, and at 0’40,
can be seen to create one stream type (audio ex. 1_3, 0’00–0’49). The inharmonic, rhythmic impact sounds that enter at 0’13 create another stream. While these streams may be spectrally related, their contrasting morphologies and supposed causes make them distinct. Two other streams are also present. A third stream, characterised by pitched pulses (based on pitches a minor 10th apart) emerges from the opening sustained material by 0’12, and then alternates with the rhythmic metallic identity before contributing to the dynamic peak at 0’38. A further, fourth stream is most noticeable between 0’22–0’24, characterised by a low-frequency, percussive rhythm in the background.
2.4.4. The Importance of Pitch and Spectral characteristics
The musical examples discussed above represent identity types with a variety of different characteristic features: source allusion, pitch motions, plays on morphological similarity and difference, and spectral permanence are all featured. The examples make clear that pitch and spectral characteristics are significant in the formation of sound identities, despite the predominance of non-tempered pitch materials within the acousmatic medium. Specific pitch values, or a certain type of pitch focus or variation (single pitch emphasis, harmonic or inharmonic clusters) may act as recurrent features, connecting sound materials even when other aspects such morphological profile appear to contrast significantly.