jwilzewske: informatics

Showing posts with label informatics. Show all posts

Wednesday, April 29, 2009

Stochastic Incipits & Continuants: Sonic Ontology in Epstein’s ‘Bloom’

B loom’ is about Time or, rather, the suspension of our conventional sense of musical Time… The solo English horn plays bass notes from which chords bloom and rise up through the ensemble. ‘Bloom’ is a series of short sections, each of which is characterized by a specific texture. The English horn is either the prominent solo voice in the texture, or it becomes the lead voice in shaping the sound of the ensemble… ‘Bloom’ ends with a giant canonic chorale, which gradually reduces texturally until all that’s left are the double-reed instruments. This gradually thins out until the last thing we hear is the solo English horn—an ending that reminds us of—but isn’t exactly like—the opening.”
— Marti Epstein, program notes.

E ven the sound of the word ‘Bloom’ is evocative—there’s an onomatopoietic rightness to it that we eagerly concur with after, say, only a minute or two into the piece. The world premiere of this composition by Marti Epstein for English horn and wind ensemble was performed by the Boston Conservatory Wind Ensemble on Tuesday evening this week, in the small recital hall of Boston Conservatory at 31 Hemenway, with Eric Hewitt conducting.

R obert Sheena, principal English horn with the BSO, was the featured soloist. Besides his BSO duties, Sheena is presently on-faculty with the Boston Conservatory, Boston University, New England Conservatory, and the Longy School of Music.

S heena’s treatment of the blossoming, organic phrases in ‘Bloom’ was expansive yet terse. In a work that is permissive of prolixity by the soloist, Sheena’s phrasing and dynamics were elegant, suggestive more than demonstrative—economical. The polyphonic ‘builds’ that Epstein refers to in her program notes—swelling and shrinking, ebbing and flowing—are a novel kind of canonical pattern. Rather than canonical forms that have more or less crisp, decidable beginnings and endings or cyclical structure, the canonical ‘builds’ in ‘Bloom’ involve non-deterministic propagation of musical thoughts or concepts between the soloist and the various sections in the ensemble.

T ime-lapse photography/cinematography of a bed of flowers opening and closing may have been the nominal motivation that inspired Epstein to compose this piece, but the physical and logical correspondences/parallels do not stop there. For example, there are gene-expression and receptor-signalling processes in biology that have closely analogous spatial features and time-oriented kinetics. So, as I sat enthralled with the performance last night I began to think, not so much about the provenance of the imagery that Epstein gave us, but thought instead of meta-concepts—how this piece is constructed, why these waves of sound propagating from section to section work the magic that they do [on us humans? on birds, dogs, whales, cicadas and other musical species?], and the ontology of the concepts underlying the musical structure and processes of ‘Bloom’.

T he English horn, of course, is fundamental to this ontology or world-view. Yes, Sheena’s realization of the part is economical, eschewing anything more than the minimum necessary, never to ‘comment’ on anything (any concept implied by the score) that should be self-evident or obvious to any thinking performer/listener. His refraining from dilatory interpretations makes Time itself more precious—a feature that is consistent with Epstein’s reverence for Sibelius ... Time made to stand still, Time stilled by Music.

B ut my saying this may seem to give too much emphasis to Sheena’s particular choices or Hewitt’s conducting or other performance details. Rather, the preciousness of Time inheres in the composition that Epstein has devised, and in her choice of English horn for the main character/protagonist.

W hat I mean is, not all instruments’ characters are created ‘equal’. The English horn’s distinctive timbre is a lucky endowment—it has an architecture (and a high double-reed back-pressure) that enables it to be ‘terser’ than most instruments are disposed to be.

A writer [musician] is someone for whom writing [musicking] is more difficult [risky; momentous; tight-rope-like] than for other people.”
— Thomas Mann.

T he ebbing and flowing of the canonical structures—the contagious crescendos and decrescendos among the sections—reminded me of the aurora borealis… its dancing, shimmering colored curtains of light in the northern night sky… Reminded me, too, of the Belousov-Zhabotinsky reaction or other autopoietic/morphogenetic integro-differential Reaction-Diffusion equations in chemistry... Or, if Time is standing still, then maybe it’s like the birth of a nebula—something celestial, galactic. Yes, ‘Bloom’ seemed to me more celestial than botanical…

T he stochastic (non-deterministic) quality of the incipits’ beginnings and the stochastic dynamics of their propagating to other regions of the ensemble as they play—the uncertainty of the stochastics decreases our attending to the incipits themselves and increases our attention to what I would call ‘continuants’. ‘Continuant’ is a fancy term used in philosophy of language and in informatics, but it really signifies something pretty commonsensical: a sub-class or descendant of a higher-level (and prior/earlier) concept or utterance. Continuants inherit most of the attributes (morphology, behaviors, capabilities, tendencies, processes, etc.) of their higher-level precursor incipits [of which the English horn part is emblematic in ‘Bloom’], but they have autonomy of their own and are influenced by their own contexts and histories.

T here are links at the bottom of this CMT post on informatics ontology engineering, for you composers who want to see whether ontology architecture may have something to offer you as a compositional framework. Your intentions and results may be quite different form Epstein’s, of course. But the ontology engineering framework and methods might well be amenable to your aims, or might at least offer you some innovative inspiration...

T he ‘Basic Formal Ontology’ (BFO) in informatics theory consists in a series of sub-ontologies at different levels of granularity. The ontologies are divided into two varieties: SNAP (‘snapshot’) ontologies, comprehending continuant entities such as three-dimensional enduring objects, and SPAN ontologies, comprehending processes conceived as extended through, enduring, and spanning time. BFO incorporates both three-dimensionalist and four-dimensionalist perspectives on reality within a single framework. Interrelations are defined between the two types of ontologies in a way which gives BFO the facility to deal with both static/spatial and dynamic/temporal features of reality. Each SNAP ontology is an inventory of all entities existing at a time. Each SPAN ontology is an inventory of all the processes unfolding through a given interval of time. Both types of ontology serve as basis for a series of sub-ontologies, each of which can be conceived as a window on a certain portion of reality at a given level of granularity.”

I n summary, one of the most novel and beautiful aspects of ‘Bloom’, to me, upon hearing this premiere performance, was these cascades of continuants—the waves upon waves of consequents: more and more [temporally- and spatially-disperse logical ——] consequents, piling up and washing over the antecedents/incipits laid down by Sheena’s English horn. The more loquacious instruments inject their colors/flavors—they could not do otherwise, any more than Sheena could prevent the English horn from being its terse self. And the organism, or flower bed, or aquatic algae bloom, or transcriptome, or receptor-signalling network, or galaxy, or whatever it is—is big enough and generous/tolerant enough to accommodate all of it. Heartwarmingly, beautifully so.

W e listened to Epstein’s new nebula blooming with an IMAX-type wonderment—floored by discovering a wideness of musical ‘peripheral vision’ that we didn’t previously know we had, awed by a deep-space ontology we hadn’t known was there. And then we stepped out of the recital hall and into the warm, starry Boston springtime night…

M arti Epstein has completed commissions for the Munich Bienniale, the CORE Ensemble, the Pro Arte Chamber Orchestra, the Foxborough Music Association, the Fromm Foundation, and Guerilla Opera, among others. She has been a fellow of the Tanglewood Music Center and a composer in residence at the MacDowell Colony. She is Professor of Composition at Berklee College of Music and at the Boston Conservatory.

Tarantula Nebula, blooming; photo © NASA

Sunday, March 22, 2009

Is Salonen’s ‘Homunculus’ Quartet a Musical Hologram?

optical holographic set-up, (c)2007 HowStuffWorks

D oes Salonen go further to say anything about music and holography? You’ve got the snippet from Salonen’s program notes about wanting to write a compact miniature that implies and acts like much more. And you’ve got the link at the bottom of the post, to the Michael Talbot Universe-as-Hologram thing. But is there a Salonen interview where he actually talks about holograms? Does he think that ‘Homunculus’ could be divided up into smaller bits and each bit would still embody all of the characters and textures of the whole [like a cut-up hologram would do]?”
— Anonymous email commenting on the previous CMT post.

I wanted to compose a piece that would be very compact in form and duration, but still contain many different characters and textures. In other words, a little piece that behaves like a big piece... I decided to call my piece ‘Homunculus’ despite the obvious weaknesses of the spermists’ thinking, as I find the idea of a perfect little man strangely moving.”
— Esa-Pekka Salonen, program notes.

T he blockquote above, which I transcribed from Esa-Pekka Salonen’s program notes, is all there is, unfortunately. I haven’t thought about it a lot (yet), but I do not think that this string quartet [its compositional structure; its acoustical properties when realized in performance] is holographic. If it is holographic, then it is a hologram of (a) ‘low resolution’ in the temporal domain and (Fourier-inverse) frequency domain and (b) represented in a nonlinear medium with ‘low quantization’ dynamic range. Just my impression.

W hich draws attention to the exoticness of holograms even now, sixty-some years after holograms were discovered/invented by Dennis Gabor. The usual notion of optical holograms is that the recording medium has linear contrast formation across a very wide range—6 or more binary bits of intensity quantization or more. And the usual notion of optical holograms—oh, cut off little a corner of the hologram and illuminate it and you still get the image of the whole thing.

B ut what’s seldom expressed—or what’s seldom conveyed in popular accounts for non-physicists, anyhow—is how the hologram image from the cut-off corner differs from the image from the whole intact hologram. Yes, the little cut-off corner is itself a hologram, from which you can cut off yet another corner and once again see the ‘same’ image of the original scene. But you can’t engage in decimation of the hologram down to a minuscule, invisible ‘corner’ of film that has only one atom, say. Or digital decimation of a file that was once many megabytes in size, down till what’s left is only one binary digit—one ‘bit’, a one or a zero.

N or is a [tiny but still visible/macroscopic] holographic ‘corner’ that is 1/1000th the size of the original—one milligram of film, out of an original hologram that weighs 1 gram—capable of showing the spatial detail or contrast that the full-size original did. Over-simplified, Future-obsessed DiscoveryChannel-ified ‘lay-audience’ excuses for ‘science journalism’ has no patience for these practical facts. Instead, we get breathless, sensationalized misinformation that backhandedly suggests that Miracles happen; that Fact is Stranger than Fiction; that infinite regressions of hologram snipping do not diminish the information contained by the progressively smaller snippets. It would be so much better if the journalists and marketers and popularizers were not running the show and if instead physicists and engineers wrote or edited the copy, for longer format shows that allowed time for a bit of real-world detail...

E very part of a hologram contains the image of the whole object. You can cut off the corner of a hologram and see the entire image through it. For every viewing angle you see the image in a different perspective, as you would a real object. Each piece of a hologram contains a particular perspective of the image, but each also includes [or contains the representation of] the entire object.”
— R. Nave, Hyperphysics, Georgia State University.

S o when you cut up an optical hologram, the contrast and information corresponding to larger-scale structures does go down. Information is lost. The projected image from a tiny corner does broadly resemble the original, but its resolution is lower and other structure ‘signal’ information may now be so weak as to be overwhelmed by ‘noise’. Holograms have a ‘transfer function’ and signal-to-noise ratio (S/N), just like any other system. And those are not scale independent.

A nd the same thing would happen with holographic music, notwithstanding Brian Eno’s and others’ gee-whiz comments. I do not think Salonen’s ‘Homunculus’ is holographic, in part because I do not think it has ‘extra notes’ in it. By contrast, most ‘minimalist’ and ‘ambient’ music does contain extra, dispensable notes. I do not see how Salonen’s string quartet can be shortened without the omitted elements being conspicuous for their absence. There is no way that the ‘many characters and textures’ that Salonen put in there will be preserved if we cut the piece from 12 minutes down to, say, 6 minutes or 3 minutes or 1 minute. No way.

I t would be interesting, though, to examine ‘Homunculus’ through affine transformations of tempo, which would be analogous to optically scaling holograms with changes in wavelength (the inverse of frequencies corresponding to the colors of light). You could do this in live performance—doubling the tempo, say. Or you could do it by resampling a digital recording of it—accelerating the tempo by some multiplicative factor but leaving the pitches and timbres of the strings intact. Are the expressive consequences of affine transformations of tempo similar to the consequences of reanimating an optical hologram in blue light versus red light? Do the phrases appear shorter? At the faster tempi, are the phrases’ cognitive/emotional “reach” and the strength of interactions with each other more limited in scope, compared to how they are at slower tempi?

L ikewise, are ‘polarization’ effects observed in holographic music? That is, when wavefront-aligning (polarizing) constraints are imposed on two or more voices in a piece of chamber music, then are the interference patterns manifested by the other parts also polarized? In other words, has the composer established a polarizing ‘medium’ through which all of the ‘signals’ are propagating, and does the resulting acoustic ‘image’ behave in measurable ways that are analogous to an optical ‘polarization hologram’?

I f the answer is ‘Yes’ then maybe there are other holographic features in there, too. If the answer is ‘No’, then we can add that as evidence against holographicness of ‘Homunculus’.

I s any of Ferneyhough’s writing holographic, do you think? Can we tell what is a hologram and what is not by examining the ‘text’ (score), in a way that’s analogous to how we can tell whether the image on a piece of film is holographic? How would we go about composing a piece that we intend to be a musical hologram?

Scaling of spatial dimension when hologram is exposed to light of different frequencies/wavelengths