Composing With Real Time Granular Sound

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Composing with Real-Time Granular Sound

Barry Truax

Perspectives of New Music, Vol. 28, No. 2. (Summer, 1990), pp. 120-134.

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Perspectives of New M usicVol. 28 n. 2 1990)

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COMPOSINGITHREAL-TIMEGR NUL ROUND

DESPITE THE M NY CH NGES which th e introduction of the computerinto the compositional process has brought about, it is remarkablehow frequently the compositional models implemented in both softwareand hardware retain the concepts and techniques of instrumental music.Perhaps these are the only ones which are familiar enough to computermusic system designers, or expressed systematically enough to be repli-cated. I n market-driven p roducts, the instrumen tal music model is the on lyone considered viable e nou gh com mercially.Central t o th e instrumental-music approach, and coincidentally to mostcom puter music systems, is the separation of soun d and stru cture. W ithinthe MUSIC V system a nd its many relatives, this separation is expressed asthe score and orchestra ; within the M ID I world it is imbed ded in the


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Real time Granular Sound

dfference between the note on , note o f f ' data and the frequently arbi-trary nature of the timbres used in th e synthesizer. A second tenet of theinstrumental approach, namely constant timbre per voice, is frequentlyenforced within these same synthesizers. Of course, the thoughtful com-poser wdl no t be misled by mere nomenclature and the resourceful experi-menter wdl always find a way to overcome limitations, i.e. the influencemay be much sub tler. But these excep tions still prove the rule. The refinedtimbral designs of Jean-Claude hsset break free from the instrumentalmusic world within the MUSIC V language; it wdl be interesting to seewhere th e M ID I world wdl find its exception.Several alternative approaches exist that un ite sou nd and structure, theones interesting me the most being those that stem from the practice ofelectroacoustic music. W alter Branchi (1983) has described the d fk re nce asthat between composing with sound , as practiced in the instrumentalapproach, and composing through sou nd . Th e acousmatic approach,usually associated with the Groupe de Recherches Musicales, provides aparticularly rich background of sonic-based thought. Among English-speaking composers, Denis Smalley (1986) has developed the acousmaticapproach the farthest with his c'spectro-morpholog~al concepts. Com-posers worlung with linguistic or environm ental materials are usually lesslikely to detach so un d from structure and m eaning, playing instead on theinterplay of these aspects. Simon Emmerson (1986) has provided an o ri g -nal insight to the classification of such approaches by his matrix of soundmaterials and sou nd syntax, each axis ra ngng from mimetic t o abstract.Over the past fifteen years of my compositional experience which hascentered on computer-assisted composition and electroacoustic studiopractice, I have sought a variety of ways of relating sound and structureintimately. A software-based compositional system, named POD (Truax1977) and later PODX (Truax 1985 ), has provided the m eans, in additionto analog s t u d o practice.Early approaches within PO D involved the m apping of timbral soundobjects on to a syntactic field. Techniques such as the tendency mask(Example 1) allowed timbres t o be introduced and gradually transformedinto variants or abruptly changed to contrasting famihes, as in onic Landscape No (1975, rev. 1977). Later work (Truax 1978) took an approachcalled polyphonic timbral construction to con struct complex timbresfrom simple frequency modulation (FM ) sources, as in my work Androgyny(1978). The next s tep involved treating timbre at a form-determining level(Example 2), as in A m 1980), where spectral families implicit in the FMmodel were used to construct the form of the entire piece (Truax 1982).Mapping timbre onto spatial patterns called trajectories was a further stepin W m e w e 1983). These approaches culminated in S o b Ellipse (1984-85), where a spinning trajectory pattern informed everything in th e workfrom the smallest base unit (one-quarter second) to the largest cyclic


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1

16-20( E N V 4)

11-15(ENV.

0c 6-10 ( E N V 2 )1-5

( E N V 5)50 60 70 80 Time-90

EXAMPLE 1: TENDENCY MASKS USED TO DEFINE TIMBRE SELECTION (TOP),FREQUENCY RANGE (MIDDLE),

AND TEMPORAL DENSITY (BOTTOM)AS USED IN THE PO ^ PROGRAM

pattern of the eleven-minute piece (Truax 1986a). Complementary timbralfamilies, both vocal and noise-like, articulated these processes and wereintimately entwined with them. It is perhaps significant that as theseapproaches brought sound and structure closer together, greater emphasiswas placed on both the macro and micro levels of the composition-asimultaneous process of moving inwards as well as outwards.An abrupt break in synthesis technique, though not in conceptualapproach, has occurred in my work over the past three years with thedevelopment and use of granular synthesis. This technique has been pro-posed (Xenakis 1971; Roads 1978, 1988) as a unique method of achievingcomplex sounds by the generation of high densities of small "grains" onthe order of magnitude of 10-20 ms duration. My recent work (Truax1986b, 1988) has shown that this technique may be implemented in real


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EXAMPLE 2: STRUCTURE OF OVERLAPPING AMPLITUDE ENVELOPES AwasB SED ON THREE FUNDAMENTAL F R E Q U E N C I E S ~ ~ , ~ ~ ,ND^^

THI S U NI T STRUCTURE IN TUR N OVERLAPS WI TH ITS SUCCESSORDASHED LINES) AFTER TWENTY-FIVE SECONDS

time using the microprogrammable DMX-1000 Digital Signal ProcessorWdraf f 1979 , thus taking the burden of data specification, storage andcalculation off bo th the user an d the machine. Synthesis techniques involv-ing additive synthesis and simple FM pairs for each grain have been imple-me nted, as well as the granulation o f stored sampled sou nd Truax 1987).hierarchy of control parameters direct the density, frequency range, andtemporal evolution of the synthesized sou nd textures.The basis of granular synthesis in the seemingly trivial grain has had apowerful effect o n my way o f thinking ab ou t sou nd . I t clearly juxtaposesthe micro a nd mac ro levels, as th e richness of th e latter lies in stark contrastt o t he insignificance of the fbrmer. Moreover, the range of densities obtain-able, from the low levels associated with human gestures through thoseperceived as rapid and virtuosic, culminating with entirely fused textures,suggests a scale of composition ranging from human proportions toabstract. Finally, in terms of the theme of sound and structure, it is clearthat t he tw o are inseparable with this technique. T he macro level structur eis best described in term s of its com pon ent sounds, and t he resulting s ou ndcomplex is definable only in terms of th e struc tural levels tha t characterizeits organization.

To date, I have composed fou r works with the granular synthesis techn ique.Th e first, iverrun 1986), is based on synthesized grains which are either


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Perspecttves of New usic

simple waveforms or FM signals. However, despite the basis in fixedwavetables, the resulting textures are always dynamically changing andrange from swarms of relatively isolated s ou nd events to fused so un d massesof great internal complexity, m uch like environm ental sou nd generally an dwater so un d in particular. T h e fundam ental paradox of granular synthesis-that the enormously rich and powerful textures it produces result from itsbeing based o n th e m ost "trivial" grains of sound-suggested a me taphoricrelation t o th e river whose pow er is based o n th e accumulation of countlessc powerless" droplets of water. T he op eni ng section of the work portrays

tha t accum ulation, as individual "droplets" of so un d gradually multiplyinto a p o w e h l broad-band texture. The dynamic variation implementedby changing variables continuously allows the piece to create a soundenvironment in which stasis and flux, so lid ~t y nd movem ent coexist in adynamic balance similar to a river which is always moving yet seeminglype rm an ent. T h e piece, find, also captures some of the awe on e feels in thepresence of the overpowering force of such a body of water, whether in ape rtu rb ed o r calm state, a nd as such it seems t o create a different m od e o flistening th an does conventional instrum ental o r electroacoustic music.Tw o m ore recent works, The Wings of Nih (1987), for com put er imagesby T he o Goldberg and tw o soundtracks, and Tongues of ngels (1988), forob oe d'amore, English horn, an d four soundtracks, are based on th egranulation of sampled sound using very short fixed samples of recordedmaterial. In the case of the first work, these samples are male and femalephonemes, and in the second piece the samples are derived from the liveinstruments. Despite the brevity of the source material, very rich texturesand complex rhythmic patterns can be obtained from it. The pitch andtimbre of the resulting so un d are determin ed by the source material unlessthe grain du ration is to o short an d a broad-band spec trum results. H ow-ever, the overlay of u p t o tw enty simultaneous versions of such sou nd , eachwi th its ow n variations, produces a "magnification" of th e original soun d,as well as the possibility of gradual or rapid movement through its micro-level cha racteristics.

The degree of magnification involved can be appreciated when it isrealized that three of the four movements of The Wings of Nih lastingapproximately twelve minutes, were derived from only two phonemes,each a bo ut 17 0 ms long T h e stereo tape is a mixdown from a n eight-trackoriginal which includes four stereo pairs of the granular material, andtherefore the vertical densities of sound are around eighty at any onemoment, and the horizontal densities range from quite sparse through toeight thou sand events per second at the very en d. T he soun ds are heard atapproximately their original pitch com bined w ith versions an octave u p o rdo wn , except towards the e nd of the first movem ent where a slow down-ward ghssando is heard.


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In th e case of the male ph one m e sequence ( tuh ), timbral changes arepossible as th e grains move (w ith changing offset) from the aspiration at th ebeginning of the sample, through the co nsonant t o the pitch o f the voicedvowel and finally past it. Microscopic timbral changes that normally gounnoticed become evident with the repetition of the overlapping grains.Fo rm ant regions become especially pro nou nce d. T he analogy in th e work isbetween the sampled visual image of the statue (the Winged Victory orNike o f Sam othrace) that forms the basis of the computer-generated imagesan d th e sampled vocal sou nd as the source o f the synthesized music. Each isbased within the human dimension but the transformation techniquesextend them towards the epic and the supra-human , as at the e nd of thefirst movement ( Album ).

In th e second mo vem ent, the Scherzo, the statue is given a head,though rather androgynously, and the phonemes in the tape part aredetache d an d realistic. How ever, each image accumulates again i nt o m oreelaborate patterns that mask the source. In the third movement ( TheIlluminate d Nike ), F M grains are used. Jus t as the image of the statueunderg oes color variations in illum ination, different carrier-to-mo dulationratios and modulation in dc es color th e carrier frequency of the tapewith timbral variations. In th e last mo vem ent, th e Coda, bo th the visualand aural elements are progressively multiplied (the wing feathers anddrapery in the visual case, and the syncopated phonemes in the musicalaccom panim ent) until fusion results. A new kind of machine emerges thatreleases the ea rth- bo un d images into upw ard fi g h t.

Spee d, rhythm ic pa tterns, an d density changes such as gradual accumula-tion or evaporation of the sound are other compositional strategies thatgranulation makes available. Speed and density, for instance, can changefro m isolated events, thr ou gh t o fast iterations (each with slightly differenttimbral characteristics), and finally result in fused textures. Stochasticpa ttern ing of th e grains can occu r over th e sam e range of densities as well,giving the sense tha t th e sou nd is coalescing o r evaporating.In th e interaction o f th e tape with the live performer in Tongues ofAngelsthis progression from speeds an d patterns within t he performance range o fthe instrume ntalist to those achievable only by the co m put er creates muchof the underlying dramatic ten sion of the w ork . We sense th e struggle of theperformer to match the virtuosity of the tape part and to transcend thelimitations of human performance. The transcendence finally materializesat the e nd o f the w ork wh en, after a gradual accelerando in b ot h parts fromsyncopated rhythms through to fused textures and continuous gestures,there is a dramatic downw ard glissando o n th e tap e. Despite th e fact that allmaterial was derived from the instruments heard live in the performance,the effect is suddenly that of a choir of voices, a transcendent image thatinspired the Biblically derived title of the work. Perhaps it could also be a


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m eta pho r for the tech nique of granular synthesis tha t seems t o break in to anew sonic domain.

Given the enormous amount of data involved in specifying thousands ofevents per second, powerful control strategies are required to make thissynthesis tec hnique effective for the com poser. T he cur ren t implementationhas developed a hierarchy of con trol levels Example 3 that include bothimprovisational and design-based strategies. At the lowest level are thecontrol parameters already described which may be altered by variouskeystroke com m and s. G rou ps o f these con trol parameters are called presetswhich are assigned to specific keys) an d these in t u rn may be incorpora tedinto a higher-level score. Alternatively, a performance of a sequence ofpresets may be saved as a score. Presets an d scores may be performed witht w o kinds o f dynamic articulation. In th e first, th e overall amplitude level isconstan t an d the preset initiates an ab ru pt change in th e prevailing textu re;in t he secon d, each preset initiates a decay in am plitude, th ereby articulat-ing it as a separate event.

COM POSITION HIER RCHY

SCORE R MP FILE TENDENCYI M SKS

CONTROL V RI BLESEXAMPLE 3 : COMPOSITIONAL HIERARCHY OF CONTROL LEVELS USED

IN THE AUTHOR S SYSTEM FOR GRANULAR-SYNTHESIS PROGRAMS

In con trast to th e ds cre te changes implemented with presets, t he secondco ntr ol rou te is via ramps, that is, pattern s of con tinuo us change in selectedparameters at a specific rate. Ramps may be ascending or descendng, as


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Real time ranularSound

well as cyclic within m inim um an d maximum values. W ith each ram p, theuser chooses which parameters are t o change (i.e. are synchronized ), atwhat speed and whether the change is in the direction of the ramp, orinverse t o it. Ram ps may be manually activated or a sequence of the m maybe prede termine d a nd store d in a ramp file. Ramps may be com bined withpresets a nd scores in any m anner, thereby mixing discrete an d continuouspatterns of change. When combined with scores, the rule is that anyvariable singled out for synchronization is no longer controlled by thescore, b ut rather by the ramp or oth er com ma nds by the user.The third compositional strategy involves tendency masks. Althoughthey are translated into the equivalent of a combination of presets andramps, they appear as graphic control shapes t o th e co mposer and hencesuggest a difkrent compositional approach (Example 4 . The tendencymask, being inherently a visual control method, presents an image of thecontrol shape based o n t he lim iting values within which choices are made.The tendency mask suggests gestures, whereas the changing numericalparameters in a ramp suggest ongoing processes. Nevertheless, th e t w omethods are functionally equivalent in terms of the way the computerimplements th em .

The tendency mask is expressed as an area within which values may bechosen . I t is on e of the simplest ways to specify time-de pende nt selection ofa variable. Although it appears to the user as a shape, it can also beunderstood as the combination of a time-dependent average value and awidth or range aroun d that average, the same t w o variables used t o co ntrolthe granular synthesis events. The width of the mask at any point deter-mines the range of choices available, thereby providing a continuumbetween deterministic and stochastic choices. The average value of themask, although an imaginary line through the middle, is usually percept-ible, particularly w he n it changes over time . Th e mask is inp ut numericallyby specifying the values of each corner plus duration. Alternatively, maskscan be gen erated as interpolations between presets; that is, each segm ent ofa sequence of masks can be derived as starting with the values of a certainpreset an d end ing with those of anothe r preset. T he difference between thetw o me thods is that with interpolation, ll segments of each mask have thesame duration, whereas with the direct specification method, no synchro-nization betw een masks is requ ired. H ow eve r specified, tenden cy masks area convenient high-level control stru ctu re that has proved useful t o com -posers working with the system. Operations on masks would provide anadditional com positional level.The current implementation, while just a beginning, has already gonesom e distance in establishing an approp riate hierarchy of levels of composi-tional control for granular synthesis, ranging from the control variables atthe grain level, thro ug h t o gro up s of such variables (presets), rates o f change


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FILE: NIKE1C

TIME SEC.) -EXAMPLE 4: TENDENCY MASK CONTROL SHAPES USED I N The Vings o h ih

TO DEFINE FREQUENCY RANGE LIGHT SHADING)GRAIN DURATION MEDIUM SHADING),MODULATION INDEX DARK SHADING),

AS WELL AS DELAY TIME BETWEEN GRAINS SOLID LINE SEGMENTS)

ramps) of th e contro l variables, and macro-level tenden cy mask an d scorest o de term ine large-scale forms.

Technology in general, a nd electroacoustics in particular, embodies knowl-edge. Computer systems must embody quite specific models about thetasks they are t o perform , hence it is very easy for them to be based onwidely accepted, traditional models simply because they are so well kn ow n.However, the design of such systems can also require us to think morecarefully ab ou t what c onstitutes the basis of ou r field of knowledge. I n myopin ion, granular synthesis cu rren tly raises the mo st fundam ental que stionsab ou t coiltemporary acoustic a nd musical knowledge.


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In taking us back to first principles, granular synthesis questions whattho se principles really are, b o th acoustically and musically. I t challenges thetrad tion al Fourier model of sou nd which states that any per io dc waveformmay be reduced t o th e sum of a set of harmonically related sine waves eachwith a different amplitude (and phase). The first problem with the basicFourier theo rem is that it ignores time; it implies that the cons tituen t sinewaves have infinite duration . In order t o deal with actual musical sou nds ,each cycle of the so un d may be analysed t o establish the time variance (o renvelope) of each comp one nt harmonic (Mathews and Risset 1969). Ho w-ever, such sou nds are no t p e r i o l c as they begin, having instead an attacktransient or b urst o f noise as the instrum ent is set in m otion . I t is interest-ing to note that this short period of time as the sound begins, when theamount of acoustic variation is the greatest, is the most critical for theidentification of the sound. It is also the part that contains the greatestam ou nt o f information. If that p art of the so un d is cut off, th e rest is barelyrecognized as coming from the instrument in question.T h e second problem with the Fourier model is that it corresponds poorlywith the psychoacoustic reality of how o u r auditory system actually proc-esses musical soun d (Roederer 197 5) . Alth oug h we can perform Fourieranalysis, i.e. distinguish separate harmonic componen ts, we can d o so onlyfor the lower harmonics whose frequencies are sufficiently far apart, andon ly under conditions where th e sound is prolonged such that we have timeto focus on those harmonics. In other words, we have to simulate theunchanging conditions implied by the Fourier theorem for it to be appli-cable. In more realistic situations, with sound densities in music involvingseveral notes per second in a m e l o l c line, possibly combined with chordsand various accompanying instruments, the aultory system uses muchmore efficient means to identify and track particular instruments. Theproblem is no t that t he F ourier approach is wrong (within its assumptions itfunc tions q uite well), bu t that it forms the theoretical basis for all oscdlator-based, and with d ig ta l technology, all wavetable-based synthesis. It s lack ofconcern for micro-level time variation continues to plague synthesizedso un d as som ethin g unnatural'.'In 19 47 the British physicist Denn is Gabor proposed an 'acousticalquantum' as the fundamental unit of sound that incorporates both fre-quency and time because it is o u r most elementary experience that soundhas a tim e pa ttern as well as a frequency pattern (Gab or 1947, 591). Inother words, the quantum is the shortest duration of sound that wdlactivate the auditory system. I t is an event, n o t merely a fixed stimulus.Althou gh the techniques of granular synthesis depart fro m the ideal Gab orgrains, they still involve the principle of building complex events from theseemingly trivial micro-level, enveloped quanta called grains. The param-eters o f these grains provide the basis for controlhng all acoustic propertiesof the resultant sou nd.


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For instance, if the component grains all have a similar frequency, theresult is a musical pitch, but as th e frequencies of th e grains are spread overa larger range, the result becomes a broad-band noise, much like the naturaltextures of wind and water. T hese so unds create a remarkable sense of spaceand volume. Similarly, if the durations of the grains are all similar, thefrequency spectrum and timbre of the resulting sound is much richerbecause of the phe nom enon of amplitude mo dulation. I n addition, wh en ashor t delay is placed between grains and then increased, th e fused granulartextu re begins t o pull apart as isolated events emerge perceptually fromth e tex ture and eventually establish rhythm ic relations. O nce global ampli-tud e c onto urs are added along with spatial deploym ent, ure have replicatedall of th e basic acoustic properties of sou nd .Th ere are also many fascinating parallels between the world o f granularsynthesis and the subatomic level of physical matter. First, of course, isGabor's idea of the quantum of sound, an indivisible unit of informationfro m th e psychoacoustic point of view, o n the basis of which all macro-levelphenomena are based. However, more specifically, Gabor postulated thatthe parameters of this quantum were frequency and time. The student ofacoustics is often taught that these are two distinct and unrelated param-eters, b ut of course, o n a deeper level of understanding they prove t o bereciprocal t o each ot he r, bo th physically a nd psychoacoustically. Th ere isalso an uncertainty principle relating the m , analogous t o Heisenberg'suncertainty principle a bo ut particles at the subatomic level. H e de mo n-strated that t he more precisely you determ ine the position o f an electronth e less you kn ow ab ou t its velocity, and vice versa. This is because velocityis th e rate of change of position. Similarly, the smaller the time window inacoustics, the larger the uncertainty (i.e. bandwidth) in frequency. Fre-quency, as the rate of change of phase, is the reciprocal of time.I n anothe r analogy to q ua ntu m physics, time is reversible at the quan -tum level. The quantum equations are symmetrical with respect to thedirection of time, and similarly, the quantum grain of sound is reversiblewith no change in perceptual quality. If a granular synthesis texture isplayed backwards it will sound the same, just as if the direction of theindividual grain is reversed (even if derived fro m natural s ou nd ). Tha t is,acoustic time has no prefrred direction at the micro level. ll of thecharacteristics that establish th e directional experience of time occur at th emacro level. Granular synthesis is in a uniqu e position t o mediate be tweenth e micro and macro time w orlds.This tim e invariance permits a time shifting of sou nd derived from th ereal world, allowing it to be slowed dow n, u p t o a thousand times or m ore,with n o change in p itch. Spectra that are normally brief instants in tim e canno w occu py virtually any duration. In my cu rrent work (Truax 198 9), asused in eauty and th edst (1989), grains are taken from the sound


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sequence at specific points, but the rate at which these points advancethrough the sequence need not be at the original clock rate. For instance,th e curre nt pointer may advance for a certain num ber o f mihse cond s, thensto p for a certain duration before continuing. Wh en clock time isstopped, the grains can move backwards through the sound with nodifference in sou nd quality. Paradoxically, by linking frequency an d time atth e level of the grain, o ne makes them independently controlled variables atthe macro level.T h e complexity and dynamic qu ahty of granular-synthesis so un d makes itan attractive alternative t o m ethod s based o n fixed waveforms or t oresynthesis models based on the transposition of sampled sound. More-over, the basic un it o r qua ntum of the grain is a potentially more flexiblebuilding block for sou nd synthesis than th e sine wave or th e use of longersequences of sampled sou nd . I t is also a very useful means of m anipulatingarbitrary groups of sound samples, particularly because the amplitudeenvelope of th e grain avoids transient clicks when extracting and com biningsample segments. When granular synthesis is used to produce continuoustextures, it has no resemblance to instrumental and other note-basedmusic; instead, its sound world is more closely related to analog elec-troacoustic music, but with greater precision of control. In certain cases,the acoustic result resembles environm ental soun ds in term s o f their innercomplexity and statistical tex ture. How ever it is used, granular synthesis isclearly situated in a df fe rent psychoacoustic domain than that occupied bymost computer music; it creates a unique sound world and suggests newapproaches t o the way music made with it is form ed.In terms of fundamental musical issues, such as compositional control,granular synthesis also requires a shift in th inkin g. I t makes us reth ink w hatth e com posing process involves. I t is obviously impossible for the composert o specify each individual grain, given that th ere may be thousands of the mper second. It reduces to absurdity the idea of total control by the com-pose r. Hierarchic levels of contro l are absolutely necessary, and at each levelth e com poser specifies key control variables o n t he basis of which all of th especific data is calculated by th e program. Interestingly eno ugh , t he struc-ture of the software that realizes the technique is also different fromconventional programm ing approaches that tend t o be linear and determin-istic. T h e granular software, in contrast, more closely resembles an organicsystem in which parallel processes are working independently, linked byaccess t o com mon variables representing the state of the world and bymessages passed between processes. The standard debugging technique ofstopping the program and stepping throug h its instructions o ne at a time ismeaningless in this case; once stopp ed, the program loses its mo st essentialcharacteristics, its time behavior and th e interaction between levels.In this kind of system, the composer functions not as an omniscient


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Perspectives of New MUSI

arbiter, but as the source of control messages that guide the overall processwithout lrectly determining it. True, other composers have used indeter-minacv and emphasized processes more than data, but granular synthesisuniquely combines these ideas into both sound and structure. My experi-ence of using the technique has also convinced me of the potential forcomputer technology to be a new instrument for musical thought, not justmusical production. The crucial difference seems to be between the com-poser being regarded simply as a user of a piece of software, and thecomposer-software system being treated as an interplay between two formsof musical knowledge. In the second case, the composer s musical insightsthat are provoked through use of the system are ideally channeled back intoit in the form of new control possibilities. In other words, the computerallows the composer s often unstated musical knowledge to be engaged inmusical actions that can lead to new compositional tools as well as to anenriched musical discourse.Yet there seems to be a trend today toward increased standardization ofdesigns in musical technology that embody very little musical knowledgeand do not encourage musical experimentation. New ideas may lead to newtechnology, but will new technology lead to new ideas? New musical ideasseem particularly elusive. The fact that the computer allows the composer asignificant choice of compositional process, not simply materials or struc-ture, seems to have been forgotten in much of the currently availablesoftware. From the perspective of the granular approach, it seems that themost promising directions may well be found on the fringes, whether inMIDI-based or synthesis-based systems, not in the mainstream of musicaldevelopment with the computer.


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Branchi, Walter. 198 3. Th e State of Anxiety. Computer Music Journal 7n o . (Spring): 8-10.Em merso n, Sim on. 1986 . The Relation of Language t o Materials. In

The Language of Electroacoustic Music edited by Simon Emmerson.London Macmillan.Gabo r, Dennis. 1947. Acoustical Quanta and the The ory of Hearing.

Nature 159 (n o. 4044 ) 591-94.Mathews, Max, and Jean-Claude Risset. 196 9. Analysis of Musical-instrument Tones. Physics Today22, n o. 2:23-30.Roads, Curtis . 1978. Auto mated Granular Synthesis of Sound. Computer

Music Joumal 2, no. 2 (Summer) 61-62. Reprinted in Fwndations oComputer Music edited by Curtis Roads and John Strawn. Cambridge,M A: M I T Press, 1985.198 8. Introdu ction to Granular Synthesis. Computer MusicJournal12 no. 2 (Summer) 11-13.

Roederer, Juan G. 1975. Introduction to the Physics and Psychophysics oMusic. 2d e d . New York: Springer.

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