For a morphology of interaction

FLO MENEZES1

Sao PauloE-mail: flomenezes@uol.com.br

In mixed electroacoustic music it is common to find theerroneous conception according to which interactionshould base itself exclusively on thefusion betweeninstrumental writing and electronic devices, whereas thecontrastbetween these sound spheres is as significant asthe fusional states. Although fusion may be seen as themost important ingredient for an efficaciouscompositional strategy concerning interaction, it isactually through contrast that the identities of spectraltransfers in mixed composition can be evaluated by thelistener. This text intends to introduce a discussion aboutthe many possibilities offered by the morphology ofinteraction between acoustic sources and electroacousticresources and structures. In this sense it tries to identifyintermediate types between the extremes of pure fusionand pure contrast, which can be established by thecomposer that sees in interactive music one of the mostadvantageous poetic realms of electroacoustic music.

1. FROM THE MORPHOLOGY OF SOUNDOBJECT TO THE MORPHOLOGY OFINTERACTION

One of the most relevant consequences of the inventionof musique concre`te by Pierre Schaeffer in 1948 was hisprogressive elaboration of a newsolfeggio, not anymoredependent on the articulations which are made possiblethrough musical notation (escrita), but on the sound andits phenomenological perception. In spite of all theoret-ical inadequacies of the Schaefferian thought – contra-dictions that are almost inevitable for a pioneer –Schaeffer’s merit is undeniable concerning a firstattempt, well-developed for an inaugural stage ofreflection, of amorphologicaland typologicalapproachto sound, contributing substantially to a new understand-ing of the sound phenomenon, either for the active musi-cian or for the attentive listener.

1Flo Menezes, composer, is author, among other books, ofMusicaEletroacustica – Historia e Esteticas (Edusp, Sa˜o Paulo, 1996) andof Atualidade Este´tica da Musica Eletroacu´stica (FEU, Sao Paulo,1998a), besides countless articles on electroacoustic music publishedin several countries (Leonardo Music Journal, Computer MusicJournal, L’Harmattan, etc.). As a composer, Flo Menezes has wonmany important international prizes, such as TRIMALCA in Mar delPlata, 1990, the Prix Ars Electronica of Linz, Austria, 1995, and theFirst Prize of theConcorso Luigi Russoloof Varese, Italy, 1996.Menezes is the founder and Director ofStudio PANaromaof SaoPaulo and Professor of Composition and Electroacoustic Music ofthe State University of Sa˜o Paulo – Unesp.

Organised Sound7(3): 305–311 2002 Cambridge University Press. Printed in the United Kingdom. DOI:10.1017/S1355771802003102

Even so, few were those who tried to take ahead, in aconsequent way, the discussion concerning the termino-logy employed by Schaeffer2. However, if these con-cepts have been anyway developed, a domain hasremained practically intact in that discussion, largely dueto the sectarian character that impregnates the severalaesthetic currents of what is today generically designatedelectroacoustic music. It concerns the problem ofinter-action between instrumental writing (escritura) andelectroacoustic resources.

2. TYPES OF INTERACTION AND THEIRLEGITIMACY

Although there are, on the one hand, some composerswho insist on the decreed death of instrumental music,and, on the other hand, others who doubt the value ofpure electroacoustic music (recorded on some technolo-gical mean and without the instrumentalists’ presence),such exclusionist postures lose more than win in thatthey remain tightly closed to the structuring and express-ive possibilities provided both by the potentially richmusical writing as well as by the inexhaustible universeof pure electroacoustic composition, known asacous-matic music. In that context, it may be extremely fruitfulif we consider the endless structural and expressive pos-sibilities of the so-called mixed or interactive elec-troacoustic music, in that both forms of aestheticapproach are incorporated in the same composition.

A preliminary verification becomes necessary: theinteraction between instrumental writing and elec-troacoustic structures can certainly be elaborated withmore effectiveness, at least in the current technical con-ditions within which this phenomenon is manifested, ifthe composer considers above all the interrelationbetween instruments (or voices) and electroacousticsounds on some fixed medium (sur support), independ-ently of whether he/she makes use of transformationalresources runningin real time (or the so-called tech-niques oflive-electronics) simultaneously with the pre-elaborated sounds in the studio.

2Besides Michel Chion’s indispensable conceptual explanations (cf.Chion 1983), it is mainly Franc¸ois Bayle (cf. Bayle 1993) and, later,Denis Smalley (cf. Smalley 1986, 1997) who make the few well-known attempts of theoretical development of the Schaefferian con-cepts.

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It is common to find a prejudicial vision within com-posers, which embraces the mix of instrumental writingand the electroacoustic medium mainly in consequenceof their appreciation of instrumental writing and its his-tory, in which the electroacoustic resources are admittedonly if these, without exception, interact in real timewith the instrumental performance, as transformationalresources accomplishedin loco and, they affirm, withthe same temporal flexibility the human interpreter has.However, although such possibilities are very interest-ing, and such an interaction that has to do with thelivearticulation of musical time is highly desirable and cap-tivating, there is nevertheless no plausible reason, infact, for the refusal of the possibilities of the interactionthat arise from the use of electroacoustic sounds fixedon some technological support as its main resource.

As a matter of fact, to this day, there are still manymore possibilities of spectral and structural elaborationin the laborious sound constitution accomplished in thestudio and registered on fixed media than in theresources, still considerably limited, of sound generationin real time originated from an interaction with thesounds of instruments. In general, the musical structuresprovided by transformations in real time are excessivelylimited to the instrumental structures themselves, while,through the use of electroacoustic sounds pre-elaboratedin the studio and its interaction with the musical writing,we deal with a much larger range of sonic possibilities,which are close to or distant from the acoustic universewith which they try to interact.

Recent developments of compositional tools – as forinstance (and above all) the Max/MSP software idealisedat IRCAM – considerably enhance the possibilities oflive-electronics, in that it becomes possible, during per-formance, to integrate other procedures such as real-timesound synthesis as well as to control the reproductioninloco of pre-elaborated sounds. Such hybrid resourcesbring to the real time domain certain aspects that tran-scend the traditional meaning of live-electronics discus-sed here, directly connected to live spectral transforma-tions of instrumental/vocal sounds. Nevertheless, evenso real time could never be compared with the unlimitedpossibilities of spectral elaboration and control the com-poser has in adiffered time.

In short, the transformations in real time, althoughconstituting a highly interesting aspect of the strict cor-relation between instrumental gestures and their elec-troacoustic metamorphosis, act relentlessly and exclus-ively in aconvergentsense, if we consider the sources ofsound emission. We will verify, however, that as muchproximity as estrangement should be longed for by amixed composition.3

3In this context, I wish to relate an anecdote. I had the privilege ofbeing invited by the GRM to take part in a concert together withLuciano Berio in theSalle Olivier Messiaenin Paris on 25 February1997. In this concert, I diffused through theAcousmonium(loudspeaker orchestra of GRM) my workParcours de l’Entite´ for

3. THE SECTARIAN THOUGHTS AND THEIRPREJUDICES

In the ambit of such placement, we observe two crucialaspects of the problem. Firstly, it is necessary to recog-nise that the critic of Boulezian stamp (in spite of thegreat value of Boulez’s interactive works), according towhich a fixed timeon support media can never turnorganically into a successful interaction, does not makeany sense, because the effectiveness of interaction won’tever depend on the fact that the electroacoustic soundsare fixed or not on some technological medium withtheir predetermined duration, but rather on the elabora-tion of such an interaction in the actual composition, inagreement with its morphologic possibilities. Con-sidering the great tape works of the history of elec-troacoustic music, countless are the relentless proofs that‘fixed time’ will, in fact, never be noticed as a ‘rigidtime’. The listener, indeed – as well stated already byMessiaen (cf. Messiaen 1994: 10) – will perceive muchless the existence of time the better the composition isorganised, the more elaborated and complex is thus themusic. The decisive factor of the ‘rigidity’ or absence of‘rigidity’ of musical time is not the physical medium,but rather the way in which the composer organises his/her structural and expressive elements. It is the structur-ing of the work that should be flexible, not its materialmedium. It is in this sense that Franc¸ois Bayle is fullyright when he states that the truesupportof sound is notmatter, but ratherenergy(Bayle 1999: 145, 151). Whichlistener would take a risk to proclaim as ‘rigid’, con-cerning time perception, works such asLe Voiled’Orphee by Pierre Henry,Gesang der Ju¨nglinge byStockhausen,Epitaph fur Aikichi Kuboyamaby HerbertEimert orVisageby Luciano Berio, to name just somehistorical examples of the best ‘tapemusic’?

The second aspect has archetypal character and is rig-orously independent of the means with which a work iscomposed. InProblems of Harmony(1934), one of hismain texts, Arnold Schoenberg speaks about the essenceof the tonal system and its double function –unifyingandarticulating functions – and searches that which isindispensable to a composition, independently of tonal-ity itself. He enunciates the principle that is required inall and any musical idea (Schoenberg says more pre-cisely: ‘In every exposition of an idea’) ascoherent con-trast (Schoenberg 1975: 278). Through the agglutinating

flutes, metallic percussion and tape, and Berio diffused his tape pieceentitledChants Paralle`les. After this event, Berio unexpectedly sentme a letter to Sa˜o Paulo, dated 5 March of that same year, with thefollowing words: ‘Your work was very interesting and I wonder,instead of using a magnetic tape, why you don’t develop your ideaswith live-electronics?’ I replied in a letter of 2 April: ‘I don’t believethat the techniques of live-electronics are up to offering the composerall the possibilities that are already accessible with the recording ontape. In general, I think that the sound structures of live-electronicsare very dependent on the instrumental structures, so that the contrastbetween instrument and electronics is not always accomplished satis-factorily. Their identity perhaps yes, but their contrast (so funda-mental astheir identity) not yet’.

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polarisation of the tonal centre, as a kind ofcentre ofgravity of the harmonic context, the tonality assumesunity with the material; through the differentiated andeven ambiguous articulation of structural elements, itreveals the contrast, the distinction, the opposition.Retaking that old lesson of Schoenberg, we can then ask:why would every interaction form in mixed elec-troacoustic music have to be seen necessarily asfusionbetween the acoustic and electroacoustic sound uni-verses?

We thus verify that if prejudice is made presentthrough thinking that is exclusively in favour of interac-tion in real time, it changes its character and becomesalso a presence in the essence of thinking that decreesthe end of the acoustic instruments.

In general, the critique of the followers of pure elec-troacoustic music is orientated by the irrevocable need,in the case of using instruments together with pre-elaborated sounds in the studio, of an absolute fusionbetween instrumental writing and electroacousticsounds, assuming therefore the presumable impossibilityof such intrinsic correlation and declaring as impracticalany interaction. To tell the truth, such criticism isderived from musicians that, in spite of their gifts in theelectroacoustic elaboration in the studio, had little or noexperience at all with musicalnotation and with themore abstract procedures that are previous even to thecoming of concrete music. Such abstract procedures aretypical of what is commonly designated as musicalwrit-ing, a concept which is indispensable to all and any con-sistent musical poetics, from that which is nearest toinstruments and most disentangled from any technologyto that which is purely acousmatic.4 It is only right toargue that, in the mixed elaboration, the composer willobtain better results if he/she constitutes an organismin which the instrumental as well as the electroacousticarticulations are not completely divorced from oneanother, as if he/she were dealing – at least during thewhole time of the composition – with two plans totallyindependent from each other and which are, as a matterof contingency, running in a concomitant way. Obvi-ously, structural interdependence and even relative auto-nomy do not implicate the absence of correlationbetween the different levels of musical writing(instrumental and electroacoustic). But in the same wayas the critique concerning an assumed impossibility ofinterest for the musical structures ‘fixed’ on a mediumis much more due to an incapacity of its partisans inelaborating, in an effective way, electroacoustic ‘writ-ing’ in the studio, the opinion concerning a presumable

4Referring once more to the pertinent (and poetic) thoughts of Fran-cois Bayle, let us recollect, in that context, his beautiful definitionof writing (ecriture) as ‘a manner of escaping of the time, of beingable,out-of-time, to summarise, to organise, to imagine, to fix some-thing that, soon after, will be reinserted in the time, in a time ofperformance (jeu)’. It is in this sense that, even amid the elaborationof his acousmatic polyphonies, Bayle affirms to be necessary ‘tobelieve on thewriting’ (Bayle 1977: 89, original emphasis).

impossibility of areal interaction between instrumentalwriting and electroacoustic sounds lapses, let us verify,of a clear limitation on the part of the musicians thatdecree it in face of the instrumental writing itself.

Here is, consequently, one of the most currentdeformations of structural thought in music since thecoming of electroacoustic composition. Having made asubstantial mutation in the concept of propermusicalmaterial, which passes, besides itsrelational character(common in instrumental music), to acquire alsocon-stitutive characteristics (spectral constitution, soundsources), electroacoustic music extends the ambit of theappointed functions by Schoenberg. Iffusionconstitutesan indispensable unifying element to mixed musicalorganisation, thecontrastbetween both sound worlds isequally essential to the discourse and the course of thecomposition! It is in this sense that, in one of the textsthat compose my aesthetic theory on electroacousticmusic, I insisted on both factors as fundamental ele-ments in the interaction between instrumental writingand electroacoustic resources (cf. Menezes 1998b).

4. DOMINANT FUNCTION

The indispensable mastership of both aesthetic spheresof the mixed composition – instrumental and elec-troacoustic – will not, thus, ever limit itself to the phe-nomenon that, in an exclusive way, merges and identifiesthem. On the contrary, it will be strategically necessarythat, in certain moments, thecontrast between bothacoustic levels captures perception so that theirfusioncan be appreciated properly.5 No matter how much ofthe dominanceof a given function (unifying in fusion;articulating in contrast, speaking according toSchoenberg) is made present in a certain work, the com-positional strategy is relentlessly nurtured by bothaspects that are subjacent to the phenomenon of interac-tion. In this way, I’ve once stated, ‘it is through the oldprinciple of binary opposition, according to which a cer-tain element is only valued if confronted with its oppon-ent, that fusion and contrast can be noticed as a domin-ant principle in a given composition’ (Menezes,op. cit.:15).

The Jakobsonian concept concerningdominanceof agiven linguistic function – in our case: unifying (fusion)or articulating (contrast) function – presupposes, on theother hand, the fact that we will hardly come across asound phenomenon in mixed music, in which there ispure fusion or pure contrast, excluding its opposite. Even

5The great masters of the history of the mixed electroacoustic musichave perceived this aspect of the problem. In my above-mentionedtext, I’ve affirmed, when pointing out the role ofcontrast, that ‘sincethe appearance of the so-called mixed electroacoustic music, as welldemonstrated by the title of the work of Maderna [to which I havereferred:Musica su Due Dimensioni, from 1952], it was obvious thatit deals with two distinctdimensionsof the musical phenomenon’(Menezes,op. cit.: 14, original emphasis).

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faced with the most convincing spectral fusion of theinstrumental with the electroacoustic spheres, hearingwill always reveal aspects of distinction between thespectral quality originating from the acoustic world andthat originating from electroacoustic resources. Sim-ilarly, it will search for a minimum contact point andsome spectral identification between these sound spheresamid the most radical contrast.

5. STRUCTURAL ASPECTS OF INTERACTION

It is necessary to say, however, that the phenomena con-cerning fusion and contrast are anchored rather in thestructural aspects of composition than merely in the‘physical’ quality of the sound emission. It is obviousthat, from that point of view, there will always be anirrevocable distinction between instrumental emissionand that which is produced by means of the vibration ofthe membrane of a loudspeaker: no matter how ‘faithful’a loudspeaker is, the sound quality that all and any amp-lification impinges on the acoustic space, impregnatingthe listening with its specific ‘timbre’, is undeniable.Incidentally, this fact implies a general need for a dis-creet amplification of the acoustic instruments them-selves in the case of mixed music, so that the instru-mental emission can approach the electronicamplification and the distinctions due merely to thephysical and consequently spatial character of thesounds be minimised.6 Such factor concerning this kindof ‘equalisation’ of the quality of sound emissions will,however, never be enough for the fusion phenomenon,in the same way as an eventual technical impedimentfor the amplification of the instrumental sounds won’tnecessarily constitute an irrevocable condition for anunavoidable contrast between both acoustic spheres(although, technically, the imbalance originating fromthe absence of amplification can, in certain circum-stances, doubtless favour such distinction between theinstrumental and electronic emissions).

Concerning the eminentlystructural aspect of thecomposition, the extreme conditions of fusion and con-trast presuppose – unlike what would be the case if theydepended exclusively on their emission quality – anentire possible range of intermediate,transitional situ-ations, in which what was merged little by little is distin-guished or, on the other hand, what was contrasting isgradually fusing and is dissolved in a third thing, thefruit of the embryonic intersection of the instrumentalwith the electroacoustic sphere. And, in that context, Iboldly say that a mixed composition of great value willbe one in which not only both extremities of that chainare constituent elements of its structuring, but also, in

6Unless a radical contrast is longed for, in which case the distinctionin sound emission is also planned by the composer in spaces wherean amplification of the instruments should be necessary to minimisethe difference between the sound quality of the acoustic sphere andthat coming from the loudspeakers.

an effective way, the systematic exploration of thesetransitionalstages between the fusion and the contrast.7

In order to explore all those stages, it is necessary thatthe composer acquires full conscience of what charac-terises, in essence, fusion as well as contrast, gainingalso knowledge concerning the transitional possibilitiesfrom one to the other of those extremes. It is in this thatresides, in synthesis, what can be called amorphologyof interaction.

What are thus the characteristics of fusion and con-trast, and what are the possibilities of structural trans-ition between these two poles?

6. THE ESSENCE OF FUSION AND CONSTRAST

In order to achieve fusion between the instrumental writ-ing and the electroacoustic structures, it will be necessaryto make certainlocated transfersof spectral character-istics from one sound sphere to the other.8 What mergeswith another thing, does it by way of anabsolute similar-itywith this other thing, of at least one aspect of its consti-tution. In this sense, dealing with electroacoustic soundswhich are pre-elaborated in the studio, the choice of theconstitutive material of departure (sound source) acquiresgreat relevance: it will be more plausible to work, on sup-port media, with sounds originating from the properinstruments used in the composition rather than with dis-parate sounds coming from other sources, without anyrelated origin to the physical materiality of the employedacoustic instruments. Although the transformations ofcourse can be very drastic, the use of similar constitutivematerial causes a certain preponderance of fusion by con-serving some of the energy profile that checks identity tothe resulting sound textures.

But such a strategy is far away from being exclusive:the structural transfers can lean on other aspects thanthe colouration (timbre) of the spectra, such as identitiesrelated to frequencies, space routes, behaviour ofmelodic and mass profiles, gesture-like constitution ofsounds (which can be identified even through the treat-ment to which they were submitted). In other words,although it is more suitable, concerning fusion, to workwith the proper instrumental sources for the elaboration

7From this point of view, theharmonic aspectof composition orsimplyharmony– in its vaster meaning, from the interval structuringto the spectral constitution of timbres – can, in my opinion, be seenas the main tool of composition for the elaboration of such trans-itional aspects as much as of the extreme situations of that chain,going from fusion to contrast and vice-versa. It is already in thissense that I have been developing, from the mid 1980s, two specificharmonic techniques, with which I elaborate most of the structuresof my compositions: thecyclical modulesand theproportional pro-jections. (Concerning such techniques or methods, please seeMenezes 1998a: 70–4, 85–92; Menezes 2002; and in English:Menezes 1997).

8In my earlier text on fusion and contrast, I had already defined thefusion as the stage in which ‘one deals with a ‘‘transfer’’ of certainsound characteristics from a sound sphere to the other’ (Menezes1998b: 15).

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of the electroacoustic sounds, the use of other soundsources does not necessarily implicate impossibility offusion and can, on the contrary, make more effective thetransition that goes from the merged to the more con-trasted sounds. It will be, therefore, through such arelat-ive distinction– just possible, in the case of using thesame instrumental sound source in the elaboration of theelectroacoustic sounds, after countless procedures oftransformation of the departure material – that the con-struction of an entire estrangement range will becomepossible, until the most evident contrast is reached (withabsence of any spectral transfer).

Anyway, in fusion, adoubt condition is established.To a certain extent, fusion implicates wilfully, on thecomposer’s part,confusionfor the listener. As I havesaid at the conclusion of my aesthetic theory on elec-troacoustic music when referring to my own mixed com-positions, ‘the listener relapses in constant doubts con-cerning the nature of what he/she is listening to: if it iscoming from the acoustic instrument or from the elec-troacoustic diffusion, if the instrumental writing isdynamically operated through spatial, harmonic, timbricand temporal interference or if the listening is being, inface of pre-elaborated structures in the studio, derivedfrom the employed acoustic instruments or at least cor-related to these sources’ (Menezes 1998a: 100). In rela-tion to the sound provenance, the more ‘confused’ thelistener is in face of what he/she hears, the more he/shewill feel the constitutive parts of a mixed piece as reallyintegrated; the ‘two plans’, which are – for the critics ofmixed music – presumably independent and united justfor contingency, become noticed asa unique plan,essentiallydiagonal to the strict lines of instrumentalemission and of purely electroacoustic sound diffusion;the instrumental emission rises then to be potentiallyprojected in the acoustic space through the electronicresources. Although in no way hegemonic, thisdoubtstatetranspires as a supreme moment of interaction.

The contrast, in turn, is anchored above all in differenceand in absolute distinction. In its more accentuatedmoments, it causes either the instrumental or the elec-troacoustic sphere to assume the structural role of thesilence, or, on the contrary, to acquire temporal and evenexcluding autonomy in relationship to the other soniclevel. In this sense, it makes it possible for the elec-troacoustic structures – unlike what happens with worksbased exclusively onlive-electronics– to take off towardsthe trip of structural self-sufficiency. Such extrememoments constitute the soloist parts either of the instru-mental writing – generally common in mixed music in itsseveral genres – or of the electroacoustic structures – prac-tically unthinkable in the poetics that are limited exclus-ively to live-electronic techniques. This momentary auto-nomy of the electroacoustic discourse may (and should!)constitute the structural elements that are strategicallyfundamental inmixedworks that take equally into consid-eration the use of fixed technological support media.

7. THE MORPHOLOGY OF INTERACTION INITS DISTINCT TRANSITIONAL STAGES

From fusion to contrast, we deal then withtransitionalstagesin which a dynamismof the spectral transfersgoverns. InATLAS FOLISIPELIS(1996–7) for an oboeplayer (playing oboe, oboe d’amore and cor anglais),membranophonic percussion (two percussion players),quadraphonic electroacoustic sounds and live-electronics(ad libitum), I tried to systematise these intermediatestages between fusion and contrast. Some references tocertain passages of this composition can serve us asexamples of our theoretical explanation. For this pur-pose, I will limit the examples to the passages elaboratedwith oboes.

In a first passage (pages 1–2 of the score),9 after theinitial synchronised attack of bongos that happens simul-taneously with the beginning of the electroacousticsounds, a ‘cloud’ of granular sounds of slightly treatedoboes emerges in the air, amid which the oboe playerbegins the performance of a figure thatinterfereswiththe electroacoustic texture and, soon after, merges intoit while staying on the same note which results from thefigurations of the electroacoustic sounds. Towards theend of this moment, the listener penetrates into adoubtsituation concerning what he/she hears, due to the fusionbetween the sonic emissions, aided by frequency iden-tity. We deal here with a case in which, at the beginningof the instrumentalist’s intervention, there is no absolutecontrast, but in which there is, in every way, a certaininterference of the acoustic writing into the elec-troacoustic one. This interference is hereconvergentwith the electroacoustic emission.

In a following moment (pp. 8–10), the oboe playerexecutes a long passage, amid which the electroacousticsounds cause interference with the instrumental con-text – again through similarity of frequencies – dynamis-ing in quadraphonic space the sounds of instrumentalorigin. It deals here with apotentialising interference.Dealing neither with fusion nor with explicit contrast,the sounds of the oboe are heard in a different way afterthe emergence of the electroacoustic sounds, by virtueof being ‘potentialised’ in space.

In another moment (pp. 11–13), the electroacousticsounds emerge from the instrumental context that wasalready established, as springing from the proper emis-sion of the acoustic instrument and acquiring autonom-ous life in order to, right after, be excited by the instru-mental gestures until incorporating them completely. Anemersionof the electroacoustic level starts from the

9The indications of pages that follow and that are associated withsuch passages refer to the not-yet-published score ofATLAS FOLISI-PELIS. The work was recorded on the CD,Musica Maximalista /Maximal Music, Vol. 5: Flo Menezes – Interactions, of Studio PANa-romaof Sao Paulo, and can be acquired on the Internet through thewebsite of the Electronic Music Foundation of New York:www.emf.org

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instrumental one, followed byexcitementof the elec-troacoustic by the instrumental sounds and consequentlywith dilution of the instrumental into the electroacousticsphere. We deal here with a phenomenon ofreflexivetransfer from an acoustic level into the other: a thing isborn from another, is interacted by the structure that wasalready established and, little by little, integrates it andannuls it in its own inflections.

After a passage of complete fusion between instru-mental and electroacoustic sounds, in perfectdoubt stateconcerning what one hears (pp. 15–20), the elec-troacoustic context sees itselfleaning on the instru-mental level: the cor anglais polarises a low frequencythat serves as support to the spectral electroacousticarticulations (pp. 20–23). Without causing absolutefusion, the instrumental figures enhance and accentuatecertain aspects of the electroacoustic context, withoutdiluting themselves into it. We deal here therefore witha typical case of a non-convergent interference(anchored by arelative distinction).

Following this moment (p. 34), an inharmonic(multiphonic) instrumental oboe sound finds back-up inthe electroacoustic context, which emerges graduallyfrom the instrumental sound, polarises the texture anddevelops until it reaches its utmost consequence,engulfing the instrumentalist’s spectrum in space. Theinstrumental sound is entirely dissolved into the universeof the electroacoustic sounds, which project ‘outside’what had been enunciated at first by the instrumentalist.It does not deal, here, with interference, since the elec-troacoustic sounds appear as ‘from within’ the instru-mental sound. We can call such a phenomenon a one-way, non-reflexive transfer, in that the transmutation ofone sphere of sound emission to the other is almostimperceptible. When the listener is aware of what he/sheis listening to, the music deals no longer with soundsoriginating from the instrument, but rather with elec-troacoustic sounds that involve him/her in quadraphonicspace.

As a consequence of that moment, the electroacousticsounds win autonomy, developing an entire texture inwhich there is no instrumental sound at all (pp. 34–5).We deal here with the more evident contrast – as alreadymentioned above – in which one of the sonic levels (inthis case, the instrumental one – although it could behandled otherwise)10 silences and does not interact withthe other. Such a phenomenon goes beyond pure contrastthrough atextural distinction(that happens, in fact, insome moments of the work), consisting of what we candesignate ascontrast through structural silence.

In another moment (pp. 37–8), the instrumental con-text, different from the electroacoustic one and concom-itant to it, refuses to be dissolved in the electroacoustic

10This is also the case in the passage of pp. 25–34, which precedes themoment ofnon-reflexive transferof pp. 34–5. In this passage, the coranglais and the two percussion players act without any concomitantelectroacoustic texture.

level, ultimately interfering with and determining thelatter, so that the electroacoustic context gradually trans-mutes itself into a transformation of the acoustic soundsand instrumental gestures. We are in the face of a phe-nomenon ofdirectional contaminationof texture. Theresult is, anyway, afusionalstate, but such a state occursthrough a metamorphosis of one of the sound sphereswhich, at first, stood out sharply from its opponentthrough contrast.

Finally, ATLAS FOLISIPELISculminates in a con-clusive passage (resultant of anothernon-reflexive trans-fer – pp. 40–41), in which the oboe player is silent andthe electroacoustic sounds, derived from oboe soundsthat were used almost in an intact manner, project theinstrumental sound in quadraphonic space through tex-tures consisting sometimes of well distributed points inspace, sometimes of rotating trajectories (pp. 41–3). Thisis a case of totalvirtualisation of the instrumentalsound.11 Such a stage, that refers the listening equally toa doubt state due to the total spectral identity of thesounds, surpasses the proper limit of thefusion throughtextural similarity (in which the reciprocity of spectraltransfers annuls a categorical distinction of what isinstrumental from what is electroacoustic). In doing so,it actually constitutes an opposition to the most evidentcontrast that is caused through the silence of one of thesound spheres, concomitant to the differentiated actionof the other. The difference between both stages of struc-tural silence of one of the compositional parts is givenexactly by the radical approach of the electroacoustictexture in relation to the instrumental performance. If inthe case ofcontrast through structural silenceeither theelectroacoustic part or the instrumental one is silent, inthe case offusion through virtualisationthe instrumentalwriting silences, against an implacable approach to theinstruments and instrumentalsimulationon the part ofthe electroacoustic context.

The figure explains the directional net going from themost obvious contrast to the most complete fusionbetween the instrumental and the electroacoustic con-texts.

8. INTERACTIVE CONCLUSION

Far from the pretension of being exhaustive, the presentapproach is not definitive and does not constitute morethan an invitation to an ‘interactive’ and maybe collect-ive reflection, on the part of the international communityof electroacoustic music, about the rich and inexhaust-ible questions concerning the phenomenon of interac-tion.

Possibly, such discussion will not achieve a largerconsensus than that developed around spectromorphol-ogy, as described initially by Schaeffer and thereafter bySmalley. Not even its understanding on the part of the

11In the score of the work, I even named such passage as ‘virtual oboe’.

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Figure 1. The morphology of interaction.

electroacoustic composer will result, necessarily, in theuse of its terminology or in effective determination ofthe compositional strategies put in practice in the act ofcomposition in the studio. In the same way as the com-poser can make use of, or entirely give up, notionsrelated to sound grain, flotation (allure), etc., while com-posing – although he/she may be in the face of grainsand flotation – nothing guarantees that the awareness ofsuch transitional stages between the most evident con-trast and the purest fusion becomes decisive in his/herpragmatic action in the moment of the realisation of his/her mixed composition.

Nevertheless, in the same way as the exercise ofmusical knowledge is carried out by means of thecontinuous accumulation of information and tech-niques, as well as through an increasingly strongerawareness of the phenomena with which one deals incomposition, I believe that such discussion, even if inan indirect way, will contribute substantially to animprovement of the practices that see in the phenom-enon of interaction between instrumental and elec-troacoustic writings one of the points of largest interestin contemporary music.

Sao Paulo, February 2001

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