Creating Multiple SpatialSettings with “GranularSpatialisation” in theHigh-Density LoudspeakerArray of the Cube ConcertHall

Javier Alejandro GaravagliaUniversity of West LondonSt Mary’s Road, EalingLondon W5 5RF, UKjaviergaravaglia@outlook.com

Abstract: This article offers an alternative for spatializing electroacoustic music using high-density loudspeaker arrays(HDLAs). It describes and contextualizes experimentation with the large array of speakers of the Cube concert hallmade during the Spatial Audio Workshop residency at the Moss Arts Center, Virginia Polytechnic Institute and StateUniversity in August 2015. The experiments were performed using the implementation of “Granular Spatialisation”(GS), a technique developed by the author for sound diffusion in HDLAs. This is based on the projection of sound usingspatial grains of “microdurations,” with ideally one grain individually addressing each speaker of the array. The articlefocuses on particular aspects of, challenges from, and strategies for using GS for the projection of sound with the Cube’sarray of 138 loudspeakers, including four independent subwoofers, while composing a new acousmatic piece that wasdiffused in the Cube at the end of the residency.

High-Density Loudspeaker Arrays: Context

This article offers insights into the practice ofworking with high-density loudspeaker arrays(HDLAs) for the spatialization of electroacousticmusic, concentrating on the implementation of“Granular Spatialisation” (GS), a method of soundprojection that scatters and transports sound in unitsof very short duration through an HDLA. I start byoffering a historical and technical contextualizationof past and present research and practice of bothsound spatialization with HDLAs and of spatialgranulation, to then focus specifically on theexperience and challenges of projecting soundand composing an acousmatic piece with theCube’s HDLA using GS during the Spatial AudioWorkshop residency at the Moss Arts Center,Virginia Polytechnic Institute and State University(Virginia Tech), 10–14 August 2015.

HDLAs: Definition and Different Types

How many speakers constitute an HDLA? The an-swer to this question is not straightforward because,

Computer Music Journal, 40:4, pp. 79–90, Winter 2016doi:10.1162/COMJ a 00384c© 2017 Massachusetts Institute of Technology.

at the time of this writing, there is no conventionstating a concrete figure. I shall define HDLA asa configuration featuring at least 40 loudspeakers(with or without an array of subwoofers), whichmay or may not allow for the individual addressingof each speaker of the array during spatialization.The number 40 is only an estimate, recognizingthat lower figures may not provide for the variety ofpossibilities of sound spatialization and localizationtypical of larger HDLAs. Furthermore, althoughcertain HDLAs are permanently mounted inside avenue (the Cube’s HDLA being a good example),other systems are mobile. Apart from the Cubeat Virginia Tech (whose configuration is explainedin detail later in this article), further examplesof HDLAs worldwide include: the BirminghamElectroacoustic Sound Theatre (BEAST) at the Uni-versity of Birmingham, UK, with a mobile HDLAconsisting of circa 100 different types of speakersand 6 subwoofers; Klangdom at the Center for Artand Media (ZKM), Karlsruhe, Germany, with 43suspended speakers and 4 subwoofers; the SonicLab at the Sonic Arts Research Centre (SARC),Belfast, UK, featuring 48 speakers, where the lowestspeaker ring is situated below the audience; TheGame of Life in Utrecht, a mobile system of 192speakers for projection of sound using wave-fieldsynthesis (WFS); and the Institut de Recherche

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et Coordination Acoustique/Musique (IRCAM) inParis also has a WFS-based system equipped with128 speakers. Some of these HDLAs work withspecially designed software, for example, the Zirko-nium package for the Klangdom at ZKM, with its 2-and 3-D controls of sound movement. The BEASTuses the BEASTmulch system, featuring real-timereconfigurable routing, channel processing, au-tomation, and various standard and nonstandardspatialization techniques—e.g., vector base ampli-tude panning (VBAP) and Ambisonics. A remarkableearly example is the Philips Pavilion, where EdgardVarese and Iannis Xenakis projected their respec-tive pieces, Poeme electronique and Concret PH,during the Brussels World Fair in 1958. Accordingto Valle, Tazelaar, and Lombardo (2010, p. 2), anestimated 350 speakers inside the Pavilion “wereorganized into ‘sound routes’ (allowing sound totravel in space) and ‘clusters’ (groups of contiguousloudspeakers playing together),” implying that theentire HDLA at the Philips Pavilion did not addresseach speaker individually, but that speakers wereorganized into sound routes and clusters with amaximum of eleven channels. Chadabe (1997, p. 61)quotes directly from lectures Varese gave in 1959 atPrinceton University and at Sarah Lawrence College,stating that the production of Poeme electronique(which was recorded on a three-track magnetic tape)used a total of 425 speakers mounted in sound routeswith 20 amplifier combinations inside the PhilipsPavilion. The sound routes allowed for achievingeffects such as sound either traveling through thepavilion or coming from different directions. Vareseadded that this was the first time in which he couldlisten to his own music literally projected into space.

The aforementioned examples notwithstanding,venues and mobile systems equipped with anHDLA are still rare, a situation that confrontscomposers, such as the five attending the SpatialAudio Workshop residency, including myself, witha problem perfectly described by Eric Lyon in hispaper at the 2014 International Computer MusicConference (ICMC):

Composers are faced with quite limited accessto performance spaces providing installedmultichannel systems with large numbers of

speakers. There are still relatively few suchstudios and performance spaces in the worldthat support composition of computer musicfor 24 or more speakers (Lyon 2014, p. 851).

Lyon goes on to state that, despite the technolog-ical advances offering numerous options for spatialmusic (compared, for example, with the technologyavailable in 1958 for the Philips Pavilion), timbrecomposition is still, by far, the predominant focusof attention in electroacoustic music.

How to Project Sound with an HDLA

This is the question that composers of electro-acoustic music will most likely ask themselveswhen faced with the challenge of diffusing soundutilizing an HDLA, and I was no exception. Hav-ing defined and described different types of HDLAin the previous section, we now look at how tomanage the high-density aspects of each HDLAfor the spatialization of electroacoustic music byconcentrating on certain appropriate strategies andtechniques. Given the diversity in numbers ofspeakers, differences in both the configuration andin the types (or combination of types) of speakers,each of the aforementioned HDLAs (either fixedin a venue or mobile) features its own—and evendisparate—characteristics. Hence, there is no uniquetechnique or method for sound spatialization withHDLAs. Instead, multiple approaches are feasible.These approaches vary substantially and depend onseveral factors, such as musical intention, aims forthe spatialization, available software, techniquesapplied to the projection (Ambisonics, VBAP, etc.),flexibility and compatibility of hardware and soft-ware, possible combinations of different softwarepackages, the disposition and types of speakers inthe array, and strategies to either use the entirearray or to divide it into particular configurationsof subarrays. The second part of the article offersseveral examples of the latter.

With regard to established techniques applicableto HDLAs, as just mentioned, certain HDLAshave been mainly designed (in some cases, almostexclusively) for the projection of sound using WFS.

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Wave-field synthesis is a reproduction techniquefor spatial sound fields, initially formulated by A. J.Berkhout (1988), that creates a virtual auditory sceneover a large listening area by using a large numberof linearly aligned speakers reproducing the truephysical attributes of a given sound. As explainedlater, WFS is tangentially relevant to this articlebecause the configuration of the majority of thespeakers of the Cube’s HDLA shows a clear lineardistribution, ideal for the implementation of WFS(although this is hardly the only technique availablehere, as my approach in the next sections shows).Another spatialization technique frequently appliedto HDLAs is Ambisonics, a spherical immersivesurround sound technique encoding the directionalinformation of a given three-dimensional soundfield to four channels (w, x, y, z) that is multiplied bytwo values: azimuth (horizontal angle) and elevation(vertical angle) covering the horizontal plane as wellas sources above and below the listener, whereasthe transmission channels carry only the encodeddata instead of speaker signals (Hollerweger 2008).The usage of Ambisonics also had an impact on myexperience at the Cube, as referred to later in the nextsections. Examples of recent developments includeRichard Garrett’s Audio Spray Gun, a tool written inSuperCollider. Presented at both the BEAST FEaSTand the ICMC in 2015, it simultaneously generatesand spatializes large groups of sound events derivedfrom a single sound sample, producing a sequence ofevents to be rendered to multichannel audio (Garrett2015).

Apart from applicable techniques, projection ofaudio with HDLAs requires the consideration ofcrucial aspects of sound, such as Denis Smalley’snotions of spectromorphology and spatiomorphol-ogy (Smalley 1986, 1997, 2007), both of whichplayed a relevant role during my experience insidethe Cube space. Spectromorphology is a term thatdescribes the temporal unfolding and shaping ofsound spectra (Smalley 1986) and spatiomorphologyis defined as the concentration on the exploration ofspatial properties and spatial change (Smalley 1997).Spatiomorphology involves several notions derivedby Smalley, for which only those related to myexperience with the Cube’s HDLA are named andbriefly described: space form, situations in which

space becomes the main source of articulation of themusical structure; spatial forms, sound structuresthat can be analyzed according to their variousperceived spatial attributes; composed space, spaceas composed onto recorded media; internal space,where a spectromorphology itself encloses a space;listening space, the place where the composedspace is listened to; diffused space, a space using amultispeaker system; and multiple spatial settings,the situation when the listener is aware throughoutthe entire composition of different types of spacesthat cannot be resolved into a single setting.

The following section describes the experienceduring my residency with the Cube’s HDLA,including the implementation of strategies fordiffusing sound with GS and the composition of anew acousmatic piece.

Creating Multiple Spatial Settingswith GS in the Cube

This section describes the experience during the five-day residency for diffusing sound with an HDLAimplementing GS, including a full description of theCube’s HDLA system as well as an account of theworkshop’s main aims and the strategies for sounddiffusion applied during the week.

The Aims of the Spatial Audio Workshopand the Cube’s HDLA System

The workshop’s requirements during the residencycomprised both the exploration in practice of theCube’s HDLA and the composition of an acousmaticpiece to be performed live in concert at the end ofthe residency, on the evening of 14 August 2015.Each of the five invited composers spent a totalof ten hours alone inside the Cube (two hours perday), and another two hours per day in the PerformStudio. The latter features a reduced 24.4 setupof Genelec speakers and subwoofers with verydifferent acoustic and architectonic characteristics,being basically a big studio-and-research area ratherthan a concert hall. Although useful for the practiceof different aspects related to our projects, it could

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only play a complementary role to the experienceinside the Cube.

The Cube’s HDLA consists of a total of 147loudspeakers in three floors (“catwalks”) usingAudio over Ethernet via the Dante software fordigital transmission of sound at a sampling rateof 48 kHz. The user can address each speakerindividually, a fact that was essential for my plans.From bottom to top, the disposition of the 147loudspeakers included 10 JBL LSR6328Ps for thestage (placed on the floor, surrounding the aimpoint); a total of 124 JBL SCS 8s, with 64 placed inCatwalk 1, another 20 on the next floor (Catwalk 2),a further 20 placed on the next floor up (Catwalk 3),and the last 20 placed in the grid facing downwards; 4Meyer UMS-1P subwoofers, one placed on each sideof Catwalk 1; and 9 directional Holosonic AS-24splaced very high in the hall (these can be movedby remote control to change their orientation). The104 JBL SCS 8s in the three Catwalks have a lineardistribution, coinciding with settings useful for theimplementation of WFS. As can be observed, theentire HDLA is quite varied in positions, numbers,and types of loudspeakers, offering numerousopportunities for experimentation with soundspatialization. It should be noted, however, that thenine Holosonic AS-24 speakers were not availableduring this residency, reducing the number ofpossible channels to 138, with 124 across the threeCatwalks and the grid, 4 subwoofers (all in the firstCatwalk) and 10 stage speakers surrounding theaudience and placed about one meter above thefloor, close to the height of the audience’s ears. Thiswas a disappointment, as I was eager to test GS withthe highly directional AS-24 loudspeakers.

GS: Main Characteristics, Aims, and Context

Before going into the details of implementing GS forthe Cube’s HDLA, the main characteristics and aimsof GS should be briefly introduced. GS combinesthe practice of sound diffusion in an HDLA withnotions and developments in granular synthesisand spatialization, including Smalley’s conceptsof spectromorphology and spatiomorphology. Themain facets of GS are based on concepts and develop-

ments about granular synthesis introduced by BarryTruax (1988) and Curtis Roads (1996, 2001), whichare predicated on Dennis Gabor’s research regarding“sound quanta” (Gabor 1947) and later, on IannisXenakis’s (1992) notion of the terms microsoundand screens, called micro-sons and trames, respec-tively, in the original French edition. Specifically togranulation in spatialization, Roads’s (2015) notionof granular spatial scattering (which sprays sound inspace in granular form and leaves parameters suchas pitch, timbre, and overall duration unaffected)is a close example. On the other hand, GS aimsadditionally for each spatial grain to ideally occupya specific location within the array with a definedshort duration. It must be noted, however, thatGS offers an alternative approach compared withother current developments in the field, such asScott Wilson’s Spatial Swarm Granulation (Wil-son 2008). The latter is conceived for a dynamic,two- or three-dimensional spatial distribution ofpreviously granulated sound across an arbitrarynumber of loudspeakers. Here grains are producedprior to their spatialization and not, as GS aims,calculated immediately at the moment of diffusion.Although this concept and use of GS can be con-sidered original, there are past examples of similarapproaches in conjunction with HDLAs, for exam-ple, in Roads’s notion of granular spatial scatteringor in Xenakis’s multichannel spatialization for hisdiverse “polytope” compositions and, in particular,in the projection of the aforementioned Concret PHinside the Philips Pavilion. Despite the similarity ofthese approaches, they all had little impact on thedevelopment of GS, which instead originated andwas directly derived from practice-led research ofmy authorship implemented in the past ten yearsfor the automatic diffusion of sound in several of myelectroacoustic compositions using Max (Garavaglia2010, 2013).

GS diffuses sound via spatial grains, which arespatial units of very short duration capable of ad-dressing each speaker individually and thereforespreading spatial grain streams rapidly across anyHDLA. The resulting spatialization creates a com-plex spatial cloud, the sum of simultaneous multiplespatial settings of spatial grains constantly changingposition within the HDLA. Hence, although GS

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can be applied to quadrophonic or 5.1 settings, itstrue potential can only be released when applied toan HDLA, where multiple spatial settings can beplaced. The following summarizes the main aimsand characteristics of GS; a more detailed discussioncan be found in my paper presented at ICMC 2016(Garavaglia 2016).

Spectromorphological and SpatiomorphologicalAspects

The intention behind GS is to reveal the structuralshaping in time of each of the spatially granu-lated sounds (i.e., their spectromorphologies) byconstantly varying their position within the multi-speaker array, revealing in the process varied typesof spatiomorphologies such as composed space,internal space, diffused space, listening space, andmultiple spatial settings.

Spatial Granulation of Sound

Sound is granulated at the specific moment of itsprojection and not beforehand, ideally with onegrain per loudspeaker. Thus, because each spatialgrain possesses, at any given time, its specific,precise, and temporally short location within themultichannel system, GS does not simulate virtuallocations. Neither does GS necessarily eliminate anoccasional combination with techniques creatingvirtual locations such as Ambisonics (as explainedlater in the article), nor is it always implementedwith only one grain per speaker, as the occasionaloverlapping among contiguous speakers of spatialgrains can also be applied by the scattering in timeof a single spatial grain among two or more speakers,which results in a softening effect of the overallspatialization.

Grain Shapes, Density, and Duration

Different table functions are implemented to shapespatial grains, mostly smooth Gaussian functions,although sharper windowing functions, such astriangular or rectangular envelopes, can also beimplemented. The grain density (control of grainduration for each speaker in the array) is determined

in GS by two parameters: (1) the rotation frequency,which establishes the time in which spatial grainscover the entire number of speakers of any givenarray, and (2) the actual number of speakers ofthat array, which implies that by a fixed rotationfrequency, the duration of spatial grains becomesinversely proportional to the number of speakers inthe array. Although (depending on each particularsituation) spatial grains can be of any duration, onlythose between 5 and 125 msec propagate soundfast enough to produce the desired rapid positionchanges of each sound’s spectromorphology withinthe space.

Distinctive Granular-Sonority Side Effect

By spatializing sound primarily with one grainper speaker, GS produces a distinctive granularside effect in the diffusion. This is the result ofnoise created by both the combination in timeof extremely short intergrain breaks between thespatial grains’ envelopes and by the density ofthe spatial granulation. With increasingly shortergrains, the side effect becomes more intense,independent of the number of speakers in the array.Thus, perception of the intensity of this side-effectsonority is affected by: (1) the shape and durationof the grain’s envelope, with Gaussian functionsproducing a rather smooth granular side effect (evenwith very short grain durations), whereas sharperfunctions (e.g., triangular or rectangular) produce amore accentuated overall result; (2) the overlappingof a spatial grain over two or more contiguousloudspeakers in a given array, which smoothesthe granulation side effect; and (3) the distancebetween the listener and the array of speakers (i.e.,the farther the array, the less perceptible the sideeffect).

Propagation of Spatial Grains

The propagation of spatial streams can be syn-chronous, with grains following each other atregular and fixed durations, but it can also linearlyincrease or decrease the grains’ durations of onesingle stream in an array of multiple speakers. In thelatter case, the term linear granular progression is

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introduced to differentiate it from Roads’s notionsof (1) quasisynchronous granulation, where theirregularity of intervals between grains is given by arandom (i.e., nonlinear), small deviation factor, andof (2) asynchronous granulation, where an irregularand randomized scattering of grains occurs (cf. Roads1996, 2001).

Strategies and Challenges Ahead of the Residency

Upon receiving confirmation to participate in theresidency, the question of how to use this particularHDLA immediately occupied my thoughts. Theanswer to this question invariably determines thechoice of a valid and purposeful strategy, which alsoincludes the selection of appropriate software. Inmy case the strategy was decided beforehand andconsisted of implementing GS, to be used as thesole method for diffusion. For this purpose diverseprototypes of spatial granulators were programmedin Max prior to the residency. Although the choice ofMax was decided at the very start of the developmentof GS in 2014, any other proposal I could havesubmitted would have most likely still used Max,observing that three of the other four composersparticipating in the workshop shared the sameview (with very different approaches and strategies,however), whereas the remaining composer’s choicewas SuperCollider. This trend depended primarily ontwo factors. First, both packages offer the requireddegree of flexibility to adapt to the challengesof diffusion of sound in such a complex HDLAsetting, something not offered by audio and MIDIsequencers such as ProTools. Second, because of theobvious time restrictions, both software packageswere available in the Cube’s computer and we allfelt comfortable and familiar with at least one ofthem.

The strategy while preparing for the residency alsoconsidered focusing exclusively on practical issuesand creative processes for the required compositionand its sound diffusion with GS, as any otheractivity (for example, to also explore the acousticalproperties of GS inside the Cube space with properscientific testing) would not have been feasiblegiven the short duration of the residency. These

decisions were crucial for an immediate start of mywork during the first slot inside the Cube concerthall.

Furthermore, my strategy for the composition wasalso planned ahead of the residency and consisted,during the months previous to the residency, ofgathering field recordings from diverse locationsto produce a soundscape, with the purpose ofdisplaying and projecting multiple spatial settingsinside the Cube via the spatial granulation of diversesound streams. The choice of field recordings asthe soundscape’s sole source of sound material wasfound to be ideal for the creation of the intendedmultiplicity of spatial settings inside the Cube, asthey introduced a variety of situations, many ofwhich occur simultaneously in the piece. Thesesounds comprise a disparate selection of sourcesfeaturing diverse spectromorphologies, such asrecordings of both bird trills and insect chirpingfrom the tropics (specifically, Colombia); of waterin different situations (for example, a fountainin Venice and Venice’s main channel, both closeto Piazza San Marco, and the seaside in Malaga);of city sounds (New York’s Manhattan Bridge);and so forth, all of which were attached to aspecific, spatially granulated stream. The sounds’spectromorphologies consisted of either relativelyconstant signals (waterfalls and insects) or of shortimpulses (bird trills), all of which required differentapproaches of spatialization using spatial grains tosimulate the perception, in time, of the naturallocation and movement of each sound stream froma vantage point close to the Cube’s “aim point.”By doing so, the overall strategy considered thecreation of an external listening space (inside theCube) by the superposition in a spatial cloud ofmultiple spatial settings within a diffused space(i.e., the Cube’s HDLA). These are made both ofcomposed spaces (the space as recorded in thosesounds) and of internal spaces (spectromorphologiesenclosing a space are here remarkably noticeable inthe recordings of New York’s Manhattan Bridge andin the bells from Venice’s Campanile in Piazza SanMarco).

For a clear perception and localization of thesound streams’ individual spectromorphological andspatiomorphological aspects, the strategy envisaged

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Figure 1. Spectrogram ofSpatial Grains: SoundscapeNo. 1.

a spatialization in either a clockwise or a coun-terclockwise direction, independent of the numberand disposition of speakers in any given divisionof the entire array, thereby avoiding a randomized(asynchronous) diffusion of spatial grains withinthe HDLA. The soundscape’s main conceptionis consequently concordant with Lyon’s views ofspatial music (Lyon 2014), as its main focus lieson its spatial conception through the projectionof diverse sounds in different sections of the ar-ray and not primarily on the timbral aspects ofits sound components. Consequently, the piece’smusical form is also driven by the overall spatialconception. Figure 1 shows a spectrogram of theentire composition, where the increase of granularstreams produces an increase in the density of thecloud’s overall spectrum, notably in the second halfwhere most spatial streams are active. By listeningto the version for the Cube’s HDLA, comparedwith its stereo reduction, the focus on the piece’sspatial conception becomes transparently evident.Because of all of these factors, the piece’s titlefinally became Spatial Grains: Soundscape No. 1,describing the aim of the composition, according toLandy’s notion of a “something to hold on to factor”for the perception of electroacoustic music (Landy1994).

Strategies During the Residency:Composing the Soundscape

In spite of all preparatory work, nothing comparedwith actually being inside the Cube, listening tosounds traveling across this unique hall. Eventhough plans of the speakers’ configuration insidethe hall were sent to all participants in the monthsprior to the residency, they only served as guidance,owing to the staggering multiplicity of possiblecombinations of spatial projection of sound withinthe Cube’s HDLA. Hence, it was only possible todecide on an efficient and definitive strategy onceI was on site. In this regard, two options wereconsidered and tested during the first slot insidethe space: (1) to use the entire array for each ofthe sounds included in the soundscape, or (2) todivide the entire array in different subarrays of nspeakers, each subarray featuring a different soundstream. To make a decision, it was vital to considerseveral aspects of the particular configuration of theCube’s HDLA, for example, the spatial perceptionof the speakers from the grid, the behavior ofthe ten stage speakers and the four subwooferscompared with the rest of the HDLA, and the typeof approach with regard to the linear dispositionof the 104 speakers in Catwalks 1–3. After testing

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Figure 2. A spatialgranulator for a 24.0 groupof loudspeakers. The upperpanels serve to chooseeither a synchronous

spatial granulation (left) ora linear granularprogression of the spatialgrains (right).

the entire HDLA during the first hour inside theCube space with diverse GS prototypes programmedin anticipation of the residency, it became clear tome that, to spatialize the spectromorphologies ofthe soundscape’s sounds and to create the multiplesettings for spatial granulation that were desired,the best option was to divide the entire array intosmaller and relatively localizable subarrays forthe spatially granulated sound streams, thereforeavoiding a possible constant usage of both the entirearray as well as of the typical linear settings in thecatwalks.

The number of speakers for each of the subarraysshould, however, be kept variable to serve thepurpose of creating multiple, differentiated spatialsettings, starting with octophonic settings forthe smaller subarrays. Following this idea, thesoundscape was finally produced by dividing theCube’s entire HDLA into eight 8.0 arrays, a 10.0array, a 4.0 array (for the four subwoofers), two24.0 arrays, and a 124.0 array. This allowed forthe use of the entire complement of 138 availablespeakers via the concurrent implementation ofthose different subarrays, each featuring its ownspatially granulated sound-stream characteristics,as a result building a rich spatial cloud through thesimultaneous conglomeration of different streams.

To achieve this, the prototypes programmed be-fore the residence were adapted during the weekto best suit both my purposes and the particularconfiguration of the Cube’s HDLA. These spatialgranulators each comprise a sound player and severalcontrols to adjust their spatial granulation parame-ters, such as: overall amplitude and direction of each

stream; function type of the grain envelope; numberof channels within the subarray; overall rotationfrequency; and type of GS, either synchronous orin linear granular progression. Figure 2 shows anexample of a spatial granulator for the 24 speakerssituated between the second and third catwalks.

The final programming of the soundscape’s spa-tialization consisted of two main Max patchers,each of which included several spatial granulatorssimilar to the example in Figure 2, albeit featur-ing different settings and configurations for thesubarrays. Through the combination of both Maxpatchers, all available speakers inside the Cube(including the subwoofers) were used. The first Maxpatcher (see Figure 3) consists of twelve spatialgranulators with a variety of subarrays, namely,eight octophonic granulators, one granulator for theten-channel stage-array, one quadraphonic granula-tor for independent usage of the four subwoofers,and two granulators with 24 speakers each. Thesesubarrays were programmed explicitly to avoid therepetition of speakers among spatial granulators asmuch as possible, thereby allowing for both a bettercirculation of each stream inside the listening spaceand also a more precise localization of the streams.This first Max patcher also includes the occasionalusage of Ambisonics, explained in detail at the endof the article.

The second Max patcher features a single spa-tial granulator (similar to the example shown inFigure 2) using every speaker situated in the threecatwalks and the grid (for a total of 124 speakers),spatially granulating a waterfall. This large andsingle subarray takes full advantage of the linear

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Figure 3. First of the twoMax patchers used for thespatialization of SpatialGrains: Soundscape No. 1,featuring twelve spatialgranulators: eight 8.0granulators, a 10.0

granulator, a 4.0granulator for the foursubwoofers, two 24.0granulators, and asubpatch for theoccasional activation ofAmbisonics.

configuration of these 124 loudspeakers by explic-itly contradicting the expected directionality ofthe spectromorphological and spatiomorphologicalcharacteristics of waterfalls, setting the diffusionin clockwise motion, which resulted in the streamcirculating linearly upwards among contiguousspeakers. By applying a linear granular progressionto the spatial grains shaped by twice-overlappedGaussian envelopes, the spatial granulation con-stantly changes duration with an upward movementin spiral form between a minimum grain durationof 3.91 msec (i.e., 500 msec for the full rotation overthose 124 speakers) and a maximum of 86.81 msec(overall rotation of 2 sec for the array). As expected,the shorter the grains, the more noticeable thegranulation side effect merging with the waterfall’sinharmonic spectrum. The desired effect was not toimitate a waterfall, but instead to simulate a largefountain pushing water upwards while the speed ofthe water flow constantly increases or decreases.

The substantial difference in the disposition ofthe outputs of each subarray inside each of thetwo Max patchers allowed both for the creation ofdifferent virtual spaces within the Cube’s entire

HDLA, as well as for a clear identification ofspectromorphological and spatiomorphologicalaspects of the soundscape’s diverse sound streams.Figure 4 shows an example of the 8.0 surrounddisposition placed within the array of 64 speakersalong Catwalk 1 for granulator 33 to 40, whichseparates each speaker with the ratio 1:8, specificallycontradicting the typical linear disposition ofspeakers in the catwalk. The other octophonicgranulators in the same catwalk follow a similarpattern, albeit using different speakers and differentparameters for the spatial granulation of their soundstreams.

Similar to the approach for the subarray featuring124 speakers, both 24.0 granulators in Catwalks 2and 3 were used throughout the piece with an as-cending or descending circular distribution includingmost of the speakers in both floors, taking advantageof their linear disposition in the catwalks. Being thefirst two granulators activated in the soundscape,each was programmed to spatially granulate soundstreams of different birds’ trills with different syn-chronous propagation and opposite directionality.The linear disposition of the speakers allowed for

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Figure 4. Catwalk 1,configured with 64 JBLSCS 8 loudspeakers, with 4Meyer UMS-1P subwoofersbehind them, and the “aimpoint” at the center of the

Cube hall. The speakersfilled in black indicate theclockwise surround-sounddisposition for granulator“33 to 40” (with aseparation ratio of 1:8).

the birds’ sounds to move contiguously and swiftly,avoiding their jumping from one side to the otherof the Cube’s space. For the granulation effect tonot interfere with the sporadic transients of theparticular spectromorphologies of the birds’ sounds,the settings for both granulators were programmedusing comparatively slow and smooth streams ofGaussian spatial grains (overlapping among threecontiguous speakers) with a duration of, respec-tively, 83.33 and 833.33 msec, which substantiallysmoothed the granulation side effect and improvedthe recognition of the spectromorphologies of the

short bird sounds. The resulting impression insidethe Cube was that several different birds were flyingand singing inside and around the upper sectionsof the hall, constantly changing their position, andthereby creating a spatial simultaneity (see Smalley1997) within the diffused space.

With special regard to the strategy for the 4.0subwoofer subarray, my intention was to apply adistinct, individual sound stream instead of simplyusing all four subwoofers synchronously for the lowsection of the spectra of the rest of the Cube’s HDLA.I was particularly interested in exploring the degree

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of sound localization for these four speakers insidethe Cube—because of the long length of waveformsbetween 3 and 120 Hz, I was intrigued to see if theindividual and precise localization of sounds fromeach of the subwoofers could or could not be clearlyperceived in a rather high room (extending over fourfloors), despite not having a particularly large floorspace. The sound sent to the subwoofers consistedof ring modulation of a 25-Hz sawtooth wave witha recording of bells from Venice’s Campanile SanMarco, where both signals were passed through twodifferent comb filters before the ring modulation.Using spatial grains with a non-overlapped quasi-Gaussian envelope and a linear granular progression(starting with a duration of 125 msec per grain andending twelve minutes later with grains of 2.7 sec),allowed for a precise localization of sounds fromeach of the subwoofers from the Cube’s aim pointeven by listening to the shortest of spatial grains.

With regard to the use of Ambisonics, the Cube’smain computer includes a wealth of software appli-cations developed especially for the space by EricLyon. One of these is a Max patcher featuring a spe-cial adaptation of Ambisonics for the Cube, calledCubisonics, which performs first-order Ambisonics(B-format) for all 124 JBL SCS 8 loudspeakers situ-ated in the three catwalks and the grid. Therefore,depending on the settings for elevation and azimuth,sound can extend to large portions of this subarray.Cubisonics was only applied in the soundscape atsix different moments to one particular octophonicgranulator each time, during which a warmer andless localizable spatialization of that particularsound stream was brought into the space, in clearcontrast to the dry and precise localization of diffu-sion when using only spatialized grains elsewherein the composition. Hence, the implementation ofAmbisonics altered the spatiomorphological charac-teristics of the chosen streams by scattering them toa larger number of speakers within the Cubisonicsarray, changing not only the composed and internalspaces of those sounds, but also simultaneouslymodifying the soundscape’s multiple spatial settingsby transferring the selected sound stream to theentire Cubisonics array. As Ambisonics was appliedonly to previously granulated spatial streams, itserved as a means for variation and enrichment of

the spatially granulated cloud and not as an alterna-tive and distinctive technique to serve the overallspatial conception of the piece.

Conclusions

The aims of testing the initial use of GS with anHDLA to compose a piece focusing on spatial aspectsrather than on mere timbre-related techniques werefully achieved. This was possible by the thoroughplanning ahead of the residency, which allowedoptimizing the use of the time available for practiceand composition. The choice of field recordingsas the main source of sound material contributedfurther to building a spatial cloud of sounds withclear spectromorphological characteristics, a factorthat allowed for an uncomplicated recognition ofthe sounds’ innate listening spaces.

Utilizing GS for the spatialization of an entirecomposition proved to be successful and reliable, asthe performance of the soundscape and its recordingin stereo during the workshop demonstrated. Gran-ular spatialization performed about equally well atevery section of the Cube (either with short or longsubarrays), and it proved excellent for diffusing di-verse sound streams effectively through the Cube’sentire HDLA with an approximately equal responsein timbre. With the exception of minor issues withCPU usage producing glitches in the granulation (acommon problem, solved early in the week by set-ting Max to use 64-bit mode) there were no furthersignificant technical difficulties during the entireone-week residency. The integration of GS withAmbisonics for certain parts of the composition alsoshowed the flexibility of GS for future combinationswith other spatialization techniques.

One important general conclusion taken fromthis experience is that the programming for theperformance of the composition on 14 Augustcan only be applied to the Cube’s HDLA, becausethe transfer to any other space and system (suchas those enumerated at the start of this article)would fully change the strategy to perform thepiece and, therefore, present a major challenge tofind the optimal approach to serve the sounds’spectromorphological and spatiomorphological

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characteristics. These differences are not onlydue to the disposition of diverse HDLAs insidedifferent halls, but also due to the use of differentspeakers for each HDLA (sometimes even withina single HDLA configuration—e.g., BEAST) andthe resulting timbral differences of their diversefrequency responses. This was particularly evidentduring the residency, when attempting to replicateexperiments originally tested in the Cube’s HDLAinside the Perform Studio, with its reduced andsomewhat different settings. Lyon provides furthervaluable insight into the subject with the adaptionof his acousmatic piece Spirits to different HDLAs(Lyon 2014).

Overall, this residency was highly enriching formy development as a composer of electroacousticmusic from a variety of aspects, including theopportunity to test GS in conjunction with strate-gies to work with HDLAs, all of which openeduncharted horizons with regard to spatializing myelectroacoustic pieces in the future.

Acknowledgments

With special thanks to Eric Lyon and the entire teamat the Institute for Creativity, Arts, and Technology,who made the entire experience truly unforgettable,also at a human level.

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