HERBSTMUSIK

The barn used for performances of Péter Eötvös' Oeldorf Group (circa 2013, but "artistically-colored").
Nr.40: HERBSTMUSIK (Autumn Music)
Musical Theatre for 4 players
(1974) [50-70 min.]

Also:
Nr.40 1/2: LAUB UND REGEN (Leaves and Rain),
final duet of HERBSTMUSIK for clarinet and viola
(1974)  [11 min.]

Development
     HERBSTMUSIK is a theatrical piece portraying a "scene from daily life".  Richard Toop describes (in his article "Stockhausen's Secret Theatre - Unfinished Projects..."), sketches for a 1969 work called OPER (Opera), where some scenes consist of "abstract" activities which create musical sounds, and some other scenes consist of more typical "daily life" activities, but which emphasize the "ambient" noises of these scenarios (or add musical signals).  HERBSTMUSIK, written a few years later, is kind of a combination of these two ideas, and portrays typical rural activities in a barn (or at least what I assume to be typical, having never played in a barn myself), set to various regular and irregular rhythms.  The activities (hammering, breaking wood branches, threshing straw, rolling around in a pile of leaves, etc...) are organized so that the sounds of their stage actions are "musical".  These were designed to create a kind "autumnal sound environment", and were probably informed by Stockhausen's own nostalgia for earlier times.

     The rural setting of the work is also inspired by a concert series held in an actual barn (see top of page), located next to Péter Eötvös' home as part of his "Oeldorf Group" activities.  This was a kind of "composers collective", where semi-exclusive performances of avant-garde electro-acoustic works were presented.  It was during these rehearsals and concerts that Stockhausen met the American woodwind player Suzanne Stephens, who would continue to be one of Stockhausen's closest collaborators in the future.

     The work is in 4 Movements which segue into each other without a break.  Each Movement has its own grouping (duo to quartet) and each takes place at one of four "stations", where the players use rural "found objects" to create rhythm and timbre modulations:

1 Ein Dach vernageln 
(Nailing a Roof)
duo (with accompaniment) A wooden house with hammers, boards, nails in 5 different sizes, and stepladders
2 Holz brechen 
(Breaking Wood)
quartet 4 piles of dry (beechwood) twigs and branches of 3-4 different sizes (with chairs)
3 Dreschen 
(Threshing)
trio A huge pile of straw (30 sheaves of grain) with threshing flails  
4 Laub und Regen 
(Leaves and Rain)
duo (with accompaniment) A huge pile of leaves, with 2 raised, functioning shower heads for creating "rain"

Each of the "stations" are shown here, going clockwise from top left. 
At bottom right is a scene from the clarinet and viola final duet.  
The world premiere in Bremen was performed by Suzanne Stephens, Joachim Krist, Péter Eötvös and Stockhausen.
Score cover. www.karlheinzstockhausen.org)
     Each movement also has one or more "inserts" where a member (or members) of the playing group moves to one of the other stations and contributes a contrasting solo sound-action.
threshing flail
Narrative
     HERBSTMUSIK is designed to create a structured musical atmosphere from the sounds of everyday rural tasks and activities.  All of the Movements act as arenas upon which the players must create "soundworlds" from the natural resources at hand: metal, wood, air, earth, leaves and water.
1st Movement: Nailing a Roof (trio)    
     This movement explores various timbres created from a hammer, nails and a board of wood.  These are used by P1 and P2 (Player 1 and Player 2) to create as many different sounds as possible (rocking, scraping or rubbing the hammer on the nails, trilling on 2 nails, creating melodies and glissandi with different intensity attacks, etc...).  P4, a young girl, enters with a clarinet and intermittently practices fragments of a simple melody ("good to whistle along with").  During this 1st movement, the hammering players also freely whistle melodic fragments in dialogue with the clarinet.  The sounds are expressed in a number of musical figures, rhythms, and timbral developments which include:
  • Hammering in syncopated, triplet, or free rhythms
  • Hammering with a gradual expansion of timbral effects (including a final phase of "magically iridescent timbres")
  • The clarinet melody is played in 3 different registers, ending in a slow tempo
  • A "twig-breaking insert" and a "threshing insert" 

    2nd Movement: Breaking Wood (quartet)
         During this movement, all 4 players create many timbres and rhythmic textures by breaking different sized twigs and branches, as well as making "ambient" noises (from dropping, picking up, rubbing, scraping, etc...).
    • Snapping, breaking sounds in irregular rhythms becoming unison, also including a brief duet in triplet rhythm
    • Snapping thick pieces and building to thin pieces (sound goes from dull to bright timbres)
    • Changing tempos (density) of the snapping from "points" to masses, including more ambient movement noises
    • A "log-smashing insert", a "threshing insert", and a "leaf insert" 

    3rd Movement: Threshing (trio)
         The trio here explores straw-threshing rhythms in triplet and duple rhythms, as well as shared rhythmic phrasing (1 beat per person).  Despite the rhythmic nature of the threshing, Stockhausen indicates that the threshing here is always relaxed and should not imply physically-demanding work.  The scene includes these elements:
    • Threshing in even, independent (polyrhythmic) strokes, with tempo variations 
    • Threshing in triplet rhythm with 1 player per beat (ie - shared figure, passed around)
    • Hissing" noises from threshing the air or lightly threshing the straw surface
    • Vocal signals ("hup", "come", "four!") to cue unison, triplet, duple rhythmic shapes, also inhaling noises and brief vocal accompaniment ("(stroke)-cha-ta-ta") to the 4/4 rhythm
    • Threshing while walking in a circle around the straw mound
    • A "hammer insert" and a "leaf insert"

    4th Movement: Leaves and Rain (duo)
         This movement has the most "story" to it, and basically portrays a playfully adolescent (yet sexually-charged) "leaf fight".  At the end, the girl uses her clarinet to teach the male player how to play a beautiful melody on the viola.
    1. The girl player engages the male in a playful fight in the huge leaf pile (which contains a hidden trough to contain the water from the soon-to-activated shower heads).  After a "furious scuffle", they both end up rolling around in the leaves in irregular and/or "polyphonic" rhythms of points and groups.  The girl yells "You!".
    2. After another "turbulent passage", the girl seems to be injured in some way and backs away from the male, before suddenly going completely wild, throwing handfuls of leaves at him.  The male suddenly goes to the house and pointedly pounds a single nail in ("hammer insert"), and then returning to the leaf pile and beginning another big scuffle.
    3. After overpowering the man, the girl retrieves a twig from the twig pile and snaps it to pieces over the prone figure of the man ("twig insert").  The man gets up and throws the girl into the leaves, instigating some playful rolling around.  
    4. P1 arrives in a "soldier march insert" (holding a threshing flail as a rifle), and after some parade movements he turns on the water to the shower heads (creating "rain" in the leaf pile).
    5. The male and female couple proceed to make noises with wet leaves (rolling around, slapping, etc...), sometimes teasing the still patrolling P1.  Eventually the slapping becomes a clapping rhythm (which will return in the instrumental final duo).   The female buries the male player with wet leaves, sometimes incorporating the instrumental rhythm.
    6. The female player leaves and then returns playing her clarinet, causing the male player to stir from the wet leaves.  Eventually the girl retrieves a viola (and bow) and presents it to the surprised but enchanted male.  The P1 "soldier" turns off the "rain" and leaves.
    7. The male then begins "learning" how to play the viola with the clarinet "teaching" the melody from the 1st Movement.  During this final duet, they move in slow rhythmic steps, following a spiral pattern to the stage exit.  The music fades away as the 2 players exit into the distance.

    Laub und Regen Final Duet
         The clarinet and viola duo starts with Clarina stating the main melody slowly.  Gradually the viola player learns the melody and the two instruments play a romantically-tinged duet, with a harmony statement of the main melody in the middle and at the end.  After the 1st successful statement of the melody (track 11, Reh.Nr. 14), the 2 players somewhat "reinterpret" the previous 4 movements of HERBSTMUSIK.  For example, the ensuing dialogue of tremolo and scalar figures are from the hammering patterns in Movement 1, and the "passing around notes" section (track 20) is an echo of the Movement 3 threshing trio.  The CD track numbers below are from Stockhausen Edition CD 32.
    CD Track Reh. Nr. Music
    1 1 Slow statement of the main melody by solo clarinet
    (1)2-5 2-7 Variations on melody fragments (tremoli, ostinati, scalar figures, wide interval leaps, etc...) ending on a flutter-tongued note
    6-10 8-13 Viola enters "badly", but is gradually taught the clarinet's melody, 1 note at a time
    11 14 Duo plays the complete melody together (fast) "successfully"
    12-19 15-25 Counterpointed fragments (brief unison "heads")
    20-23 26-30 Passing around parts of a 3-note fragment (echo of Mvmt 3 threshing rotation)
    (23) 24 31-33 A few unison harmony events mixed into dialogue
    25-28 34-38  Counterpointed fragments 
    29 39 Final statement of the complete melody in high register

    Live Performance
    YXUS Ensemble:



    Concert version of the 4th Movement's final duet: LAUB UND REGEN (Leaves and Rain), version for clarinet and basset-horn (Petra Stump and Heinz-Peter Linshalm, 2003 Stockhausen Courses):

    Sound Impressions
         Though I've never experienced this work in its full form, I can imagine it as being really very funny.  In fact, the score specifically asks for "comic interpretation" at some points, and I can see that this would be very easy and natural to do in the context of the scenes.  The final clarinet and viola duo is a very beautiful work using relatively "romantic-style" writing (though it starts out exactly as described above: the viola player "doesn't know how to play" until several bars into his section, and until he learns how to draw a bow smoothly over the strings, it sounds pretty scratchy...).  In any case, HERBSTMUSIK, like FRESCO, is a gem of a piece which could use more recognition (and a video release).  Some of the ideas here would clearly echo on into works of the future (including MUSIK IM BAUCH 's switches, HIMMELS-TÜR's wooden drumming, and certain "teaching/learning" scenes from DONNERSTAG aus LICHT, such as MONDEVA and MISSION).

    Links 
    LAUB UND REGEN on Stockhausen Edition CD 32
    Buy the Score
    HERBSTMUSIK Wiki
    2013 Performance clips, Südgelände Berlin (Vimeo)
    2013 performance webpage with YXUS Ensemble
    "Stockhausen's Secret Theatre - Unfinished Projects from the 60s and Early 70s " (Richard Toop, Perspectives on New Music 36.2)
    Oeldorf Group Wiki Entry

    PLUS-MINUS

    Symbol Matrix page (1 of 7)
    (© Universal Edition)
    Nr. 14: PLUS-MINUS
    for any number of instrumentalists
    (1963, rev. 1974)   [duration open, probably well over an hour]

    Development
         Developed at the seashore on a vacation with artist Mary Bauermeister and then given as an exercise to students at his newly-founded Cologne Courses for New Music, this work basically functions as a composition assignment (complete with 35 rules, 318 "puzzles" and 7 pages of "answers").  The published score is titled "PLUS-MINUS, 2 x 7 Seiten für Ausarbeitung" (2 x 7 pages for working out, or realization).  Stockhausen himself never found the time to complete this "assignment", and no "official version" of PLUS-MINUS has ever been recorded.  In a sense, it's probably the closest one can get to attending a Stockhausen composition course in the 1960s.

         The chronological timing of the actual ideas in PLUS-MINUS is very fascinating, considering the works before, during and after it.  Around the same time as writing PLUS-MINUS, he was revising PUNKTE and finishing MOMENTE.  The following year would see the first experiments with ring modulation and live electronics (MIXTUR, MIKROPHONIE I & II), but it would not be until 4 years later (after HYMNEN was completed) that Stockhausen would revisit the idea of "plus minus" event transformations in PROZESSION.  With this chronology in mind, the use of such open-ended compositional devices and iconoclastic notation foreshadowed what would come.  However, at the time, Jonathan Harvey claims that he saw "incredulity, bewilderment and hostility in the seminar that Stockhausen gave on it at Darmstadt, shortly afterwards."

    Melodic Life Cycles
         The below explanation uses terminology from an analogy which is not part of the score at all, but which I personally find easier to use.  Below are "my terms", with the original score terms in quotes:
    • Character: "Types"
    • Body: "Central Sounds"
    • Limbs: "Accessories"
    • Tools: "Subsidiary Notes"
         For the purposes of this article I'm going to take the liberty of using my own terms (apologies to score purists, but I don't feel like typing out "Zentralklang" 50 times).

         The basic idea of PLUS-MINUS is that 7 musical motifs, or "Characters", appear over and over again in different sequences (basically one Character at a time, but it's also possible to have multiple PLUS-MINUS layers happening at the same time).  Not every Character appears the same number of times on a page, but each page "features" one character more than any another (Fibonacci sequence distribution).  These Characters are "born" with a central chord ("Body") associated with 1 to 3 free pitches/noises ("Limbs").  A Character may often appear with a "Tool", which is a collection of 1, 2, 3, 5, 8, or 13 grace-notes/chords to be reordered/stacked in any way. 

         The Characters appear chronologically according to Event boxes (read left to right in rows on the Matrix page), and each consecutive Event is affected by the previous Event, in that the featured Character must act in some way "more than" or "less than" the previous Event's Character (louder/quieter, taller/shorter, talkative/taciturn).

         Often when a Character reappears, it may have either "grown" (by adding a new Limb or by cloning itself) or "regressed" (by cutting off a Limb or by killing off a clone).  The score rules often give the student composer both options of growing or regressing a Character (Ex. "+1/-1").  If a Character regresses into the negative (the degree of growth/regression goes from +13 to -13), then a "photographic negative" of the Character is introduced.  If the growth goes above +13, the Character is "reborn" into a new initial state, and if below -13, the Character is "killed off" (it is actually possible to kill off all 7 Characters before all of the Events have been played).

    The Characters:
    (All score excerpts © Universal Edition)
         The first step is to pair up the 7 symbol matrix pages to the 7 notation pages (chords/branching notes). Each pair of pages makes about 10-15 minutes of music.  All 7 pairs of pages should be played, but most recordings only feature 1 page.

         Each boxed symbol of a matrix page is an Event.  The sequence of the 3 main elements (Body, Limbs, Tools) is read from left to right in each Event square, and simultaneous events are stacked polyphonically (stacked parts can be layered rhythmically in this case).  There are 7 Characters (character types), listed below as combinations of Body chords (B) and Limb notes (L) (Tools are not part of the Character type, since they change from Event to Event):
    1. L - B (meaning L then B)
    2. L + B (meaning L and B stacked)
    3. B - L (etc...)
    4. L - B - L
    5. (L + B) - L (shown in Event 32, below)
    6. L - (L + B)
    7. L - (L + B) - L

         In each recurrence of a Character, the Body chord essentially stays the same, but the Limbs may be different pitches/timbre. At the same time, each Character reoccurrence should be "recognizable" even with growth additions/subtractions (this suggests that the Limbs and Tools should have some kind of Character-specific shape).  Each of these 7 Characters must be assigned one of 7 chords (I-VII, at right) from its paired notation page, and must use this chord for every one of its appearances (though it is possible to transpose the chords).

    Matrix Event Squares
    1 square box is 1 Event
    (this is Event 32, which features Character 5)
    These are the individual parts of an Event square (above):
    1. Body (circle): Assign the Character chord (possibly arpeggiated) from the notation page.
    2. Limbs (triangle/diamond/spot/?):  Assign short/med/long/indeterminate free pitches/noises (same register as the Body chord), each Limb occurrence following as fast as possible, but with the durations clear.  In Event 32 above, the 2 diamond Limbs above mean 2 medium-length Limb notes/sounds, with one during and one after the Body chord.
    3. Tools (eighth-note stem without notehead): The number here indicates which group of grace-notes (1-6 below) on the paired notation page to use.  The grace-notes/chords in each group can be permutated or stacked freely.  The flat/sloping line indicates fastest speed (-), accel. to fastest speed (/), or ritard (\).  In Event 32 above, Tool 5 is indicated, so Group 5's 8 notes must be used, with a ritard.
      A set of 6 Tools (branched notes) used on 1 matrix page
    4. Flags: When a Flag containing a positive/negative number appears above a Character, it indicates an addition/subtraction to the number of repetitions of the Body, Limbs, or both (the Tools notes may or may not increase proportionately, since more hands should have more hammers, right?), and stays in effect for all recurrences of this Character until a new Flag appears.  Also, the additive effect is additive and not exponential, so adding 1 means adding an original Character part, not a clone group.  The Flag only takes effect from the 1st recurrence (not the original flagged Event).  In Event 32 above, the composer is given the choice to either add or subtract 2 limbs, bodies or whole characters (cloning/killing). 
      • If the number becomes 0 or negative, Limbs and Bodies are expressed as 2 "negative bands", with the number value represented by pauses.  The negative bands should be like a "photographic negatives" or "ghosts" of the original sound.  
      • If a Character reaches 13 iterations (13 repeating clones), it starts again with 1 of the original Character, but with a new interpretation. If it reaches -13, it disappears and is skipped for the rest of the composition (is "killed off"). 
    5. Hairpins (</>): these symbols contain numbers indicating changes in lowest pitch, register, dynamic, or duration of the event (< means more, > means less), compared to the previous Event.  The numbers refer to degree of change, and the number can also be spread over more than 1 parameter.  These degrees of change can be amplified and spread over a "section" (ie - the composer creates a form structure of sections based on musical trends in the Events).  In Event 32 above, the Event must be greater than Event 31 by 1 degree in a parameter.
    6. Transition: symbol indicating whether the Event is followed by a short/long pause, segues immediately into the next Event, or overlaps into the next Event.  In Event 32 above, the "v" indicates a short rest before the next Event.
    7. Articulation:  "Damping/muting", accents (with echoes), reg/irreg. rhythm, or K for "combination" (above).
    8. Timbre: These solid and dashed lines indicate the timbre of the Event parts (divided into combinations of soft/hard sounds(pitches)/noises)).  Sounds, noises and sound-noises are analagous to vowels, consonants and semivowels.  In Event 32 above, the timbre is to be a mixture of soft sound-noises.
    9. Downward Arrows: More than 1 Layer (up to 7) of a PLUS-MINUS realization can be played at the same time, each with.a "signature" sound characteristic.  The thick downward arrows are used for coordination of Events between multiple Layers (longer arrow = more unison Layer Events transitions).  In Event 32 above, the Event begins simultaneously with many other Events in other Layers (if any).
    10. Staircases: The bottom right "staircase" figures control the degree of harmony or dynamics between layers by exchanging/deleting notes between simultaneous Events and controlling swelling/fading envelopes.  In Event 32 above, the indication is to replace this Event's pitches with the pitches from a simultaneous Layer's Event.
         Some Events have thick borders and some are empty (first, fourth and last Events on top row of Matrix page above).  The thickly-bordered Events are "time windows" (such as used in MIKROPHONIE II), inserted into the blank Event boxes on other pages, depending in the upper page corner arrows.

         If more than 1 Matrix page of Events is being realized, the next Matrix page will continue the "saga" of the same 7 Characters (if they haven't been killed off), but their Body chords and Tool sets are newly-assigned from the new Matrix-page's complementary notation page.  Stockhausen asks that an interpreter send the publisher the details of the last Event realized in his/her version, so that the "next" realization can continue on from it....

         (The above paragraphs don't include many other more detailed rules from the score, which have to do with transposition conditions, etc...)
      Tool Trends
           There are 7 pages of Matrices, and 7 notation pages of chord/grace-note elements, to be matched one to a page.  Below are some general characteristics of each of the 7 pages of Body chords and Tools groups.  For the most part, the kind of Tool set (out of the 7 below) used in a Matrix page can give a strong identity to that particular page.
      1. wide chords, chord clusters
      2. wide chords, with a couple clusters, diads and a few single notes
      3. wide chords, with a couple clusters, major and minor 2nd diads
      4. wide chords, with a couple big clusters, wide grace note leaps
      5. medium-spaced chords with a couple big clusters, range descending downwards, scalar figures and single notes
      6. wide chords with a couple big clusters, 2-note tremolo figures
      7. medium-spaced bass chords, single notes
      Realization
           The above paragraphs describe what the resulting composition must be but leaves the steps of how to actually do it up to the composer.  If I ask myself how I would proceed, this is a possible answer:
      1. Pair up the Matrix and notation pages.
      2. Identify all of the Character 1 types and fill them with one of the 7 notated chords for each page.
      3. Fill all of the Limb parts for Character 1 and and give them some kind of unified signature shape.
      4. Fill in the Tools for Character 1 (also maintaining a unified shape if possible)
      5. Apply the Flag growth/regression marks.
      6. Repeat for the remaining 6 Characters.
      7. Starting from the first Event, and going one by one, fill in the timbre articulation markings, hairpin transformation rules and transition markings.
      8. If more than 1 layer, apply the "staircase" and "down arrow" coordination markings.
      9. Move the Time Windows into the appropriate pages.
      Recordings
           There are 2 commercially-available versions of PLUS-MINUS on CD.  Elizabeth Klein performed a 1-page, 1 Layer, solo piano version, realized by Nils Holger Petersen.  This recording is a very straightforward representation of the growth of the 7 Characters (actually listening to this version inspired the "Characters, Body, Limbs, Tools analogy).  Peterson only used 1 matrix page for this version and it lasts about 13 minutes.  In 2002, the Ives Ensemble recorded a 2-Layer version, with each Layer given to a mixed ensemble (left and right in the recording).  One Layer was realized by Christopher Fox and the other by John Snijders.  This one also has a strong periodic character, and for its "negative band", it uses taped excerpts of ambient rehearsal noise.  It's a full 51 minutes, so I wonder if it's a complete double realization of all 7 Matrix pages.  What makes this interesting is the arranging of the character elements over multiple instrumental timbres, as well as the mixture of synchronous and asynchronous Event transitions.  The article that Christopher Fox wrote about his experience creating a performance score out of PLUS-MINUS ("Stockhausen's PLUS MINUS, More or Less: Written in Sand", Musical Times, 2000) is a very interesting read and also gives a description of several other versions, including one by Gavin Bryars which used excerpts of Tiny Tim and field recordings of pissing elephants for the "negative band" sounds.  Stockhausen did not approve of this...
      (from "Stockhausen's plus minus, More or Less: Written in Sand", Courtesy C. Fox)
      (from "Stockhausen's plus minus, More or Less: Written in Sand", Courtesy C. Fox)
      Impressions
           Because of the reiterative nature of this piece, the result usually starts out with a wide variety of short melodic motifs, but as the parts multiply in repetitions, a kind of periodic structure results.  Theoretically, it could be possible to get a maximum of 13 repeating Body chords and 39 Limb notes from just a single 3-Limbed Body (13 + (3 x 13)), which of course, will sound pretty "groovy".  This is also reinforced by the instruction to allow polyphonic parts to be expressed rhythmically.  In general, this work usually doesn't produce a "points and groups" kind of piece, but instead possibly creates something closer in shape to STIMMUNG, which would come 5 years later.  Come to think of it, a multi-Layer a capella version of PLUS-MINUS would be a good companion piece to STIMMUNG.

           Apparently many versions were created in Stockhausen's composition class (some of them by now well-known composers), but few recordings of this work exist, and there is no "official" version in the Stockhausen Complete Edition CD catalog.  The openness of the score allows for a "co-composer" to imprint his or her own style on it to a very high degree, so maybe he felt that any realization/recording would have enough of the co-composer's contribution to make that one essentially "official".  Or perhaps, had Stockhausen lived long enough, he would have eventually worked out his own version, and would have then released that as an official recording.

           Another possibility is that after he heard the results he was getting from his students, he lost interest due to the unavoidable appearance of so many regularly-repeated melodic motifs.  His next "plus-minus" work would be PROZESSION, which would use excerpts from more "thorny" works like GESANG DER JÜNGLINGE , MIKROPHONIE I and KLAVIERSTÜCK XI to act as initial character types - keeping the idea of transformation, but jettisoning the iterative elements.

      Links
      Puchase the Score
      Wiki Entry
      "Stockhausen's plus minus, More or Less: Written in Sand" (Christopher Fox, Musical Times, 2000) 
      Some Recordings:

      KLAVIERSTÜCK XI

      KLAVIERSTÜCK XI
      (with my color variation of a Lindsay Vickery slide)
      Nr. 7: KLAVIERSTÜCK XI (Piano Piece 11)
      (1956)  [approx. 14 min.]

      Introduction
           In the earlier analysis of Piano Pieces 5-10, I described the isolated phrases in those works as being in a way "snowflakes in a snowstorm".  In this 11th piano piece, that analogy becomes more appropriate than ever.  However, from a pianist's point of view, it may be more apt to use an "autumn leaves" analogy.  Here, 19 musical "leaves" are spread in front of the player.  He picks one up, "plays" it, returns it to the pile, and then picks up another to play (however, the way he plays this new leaf is affected by what he saw in the previous leaf).  Sometimes he will pick up one that he's chosen before, but he plays it anyway.  However, if he realizes that he's picked up the same leaf 3 times already, he stops, and the performance is over.  In Piano Piece 11, each leaf is a few measures of score, and at the end of each score fragment is the indication of how to approach the next chosen musical fragment (in the terms of tempo, dynamic, and articulation).  Instead of a "pile of leaves", all of these musical fragments are scattered over a huge sheet of paper, and the pianist chooses the phrases randomly.  He stops after he has hit the same fragment a 3rd time.

           (I should mention that Stockhausen has never called these 19 score fragments "leaves" (as far as I know), but I just find it handy to think of them that way.)

      Polyvalent Form
           Because of the nature of this piece, there can be an almost unimaginable number of versions.  Each version could start from any one of the 19 "leaves", and end on any one of them.  This is an example of what is sometimes called "open-form" or "polyvalent form", since the composition itself has no set structural arc.  One idea that Stockhausen is exploring here is that each of these leaf fragments create their own "vibration" or color.  In the previous Piano Pieces, grace note "satellites" and "halo tones" were used to create a resonating color over a central note.   In this piece, each leaf (which also has its own internal central notes and satellites) could be considered a single central tone by itself, and the tempo/dynamic/articulation instructions at the end of each leaf are a kind of "resonant-coloration" which affects its surrounding "satellite" leaves. 

           Structurally, if one thinks of each one of these 19 leaves as a single note-entity (as just described), the chance sequencing of the leaves functions more or less the same way as putting these leaves into a serial sequence.  The basic purpose of serialism is to produce variety and unpredictability, and the method employed here can produce the same kind of unpredictability.  Naturally this "eye-contact serialism" is not going to be as "pure" as in a case where these leaves are put into a specific, non-repeating "leaf row", but since the previous piano pieces already covered serial organization on different time-scales, perhaps the idea of an open-form work which could produce a large variety of structural outcomes became much more important.  However, ironically, some pianists prefer to "pre-program" the sequence and play the same sequence of leaves from performance to performance (probably because it was simply too hard to do it the "honest way").

           Stockhausen points out that it doesn't really matter how these leaves are sequenced - in the end it's still a pile of leaves.  The work itself has its own unique "vibration".  "Piano Piece XI is nothing but a sound in which certain partials, components, are behaving statistically...  If I make a whole piece similar to the ways in which (a complex noise) is organized, then naturally the individual components of this piece could also be exchanged, permutated, without changing its basic quality."  (Conversations with the Composer, Jonatan Cott).

      Rhythm and Pitch
      6 of the 36 possible rhythm patterns from the "final matrix".
      (from Truelove's "The Translation of Rhythm into Pitch in KLAVIERSTÜCK XI")
           The melodic material of each leaf was created through a fairly complex method of cross-breeding rhythm patterns (above), layer density and articulation tables (tremoli, trills, fermatas, satellite grace notes, halo tones, clusters, etc..).  The methodology is very structured and mathematical, yet there are many places where Stockhausen broke from the math for the sake of musicality ("composer intuition").  

           From a pitch-perspective, the notes were derived from proportionate durations contained in the melodic rhythms.  For example, if two notes had a proportionate duration ratio of 3:2 or 2:3, an interval of a 5th was called for (sometimes augmented or diminished).  A ratio of 2:1 would dictate an octave (sometimes flatted or sharped).  In Stephen Truelove's KLAVIERSTÜCK XI thesis (which was a major source of info for this particular section), he claims that these flat/sharp "alterations" were methods to make the work "atonal", but Stockhausen responded that these "off" notes are just approximations of harmonic relationships (I assume this is related to discrepancies between equal- temperament and just intonation).  In any case, the idea of translating rhythm into melody is a logical one because rhythm can be turned into pitch if played very fast.  In other words, if 2 different rhythms were looped at super-high speed, they would sound like 2 different noise drones, and if the rhythms were periodic, actual pitches could be heard.  If the ratio were 2:1, an octave interval would be produced (this idea is very important in the electronic work KONTAKTE).

           Additionally, after the melodic shapes were derived from rhythmic proportions, pitches could be freely shifted to higher or lower octaves, and in general, longer note values were given lower register pitches.  Satellite grace notes did not follow any duration-ratio rule (since they are to be played "as fast as possible", after all), so these pitches were chosen intuitively. 

      Score
           The player starts by choosing one of 6 tempi and playing the first randomly-selected leaf.  At the end of that leaf is the tempo, dynamic and articulation for the next randomly-chosen leaf.  After a pause, or during a sustained chord, the next leaf is chosen and then played with the indicated markings.  If a previously-played leaf is chosen a second time, the leaf is to be played in a slight variation, such as in a new octave (like looking at the backside of a leaf?).  Not every leaf needs to be played in a performance.  If the same leaf is chosen a third time, the pianist ends the performance (without playing the thrice-chosen leaf).

           One of the interesting things to consider is that each of these 19 leaves can be played in 19 different variations (depending on the tempo, dynamic and articulation instructions from the previously-played leaf).  Out of these 361 leaves, theoretically anywhere from 2 to 39 could end up being played for a given performance. The number of possible performance sequences is....well, very big.

           Below are 5 of the 19 leaves (melodic fragments).  Ellen Corver recorded 2 versions of KLAVIERSTÜCK XI on Stockhausen Edition CD 56.  The first version (Disc 2, Track 2) starts with the 3rd and 4th score examples below. The second version on Track 3 begins with the 5th example.  All of the score excerpts below are copyright Universal Edition and www.karlheinzstockhausen.org.
      This leaf descends into a long trill.
      T1 indicates that next leaf should be played at the lowest speed, the indication "N" means "neutral" articulation.  The "(8....)" at top means that the 2nd time this leaf is played, it should be an octave higher.

      This leaf has large interval leaps.
      T6 means that the next leaf is to be played at the highest speed.  The "(8....)" at bottom means that the 2nd time this leaf is played, it should be an octave lower.
      (with wide and narrow tremoli; the articulation for the next chosen leaf must use staccato attacks with silent redepressions)
      (with pedaling and halo chords)
      (dense syncopation with intermittent pauses, halo chords, etc...)

      Live Performance
      Prodromos Symeonidis, February 2006

      Sound Impressions
           The general textural language of this piece fits very well as somewhere in between KLAVIERSTÜCK VI and X (naturally).  Because of the pauses and fermatas between (and inside) the fragments, there is a natural tension and release in the flow, and plenty of time to absorb the silences.  Because of the open nature of a performance, each can be something of a new experience.  However, unlike a "set" work where repeated exposure can help the listener become familiar with larger dramatic arcs, this one could be different every time (and of course, there is no "normal" score to follow visually).

           Stockhausen considers the whole work to be an atomized timbre, stretched out over several minutes, and I suppose one could listen to it like that, but perhaps there are a few other ways to follow this work.  One possibility is to try to get a feeling for each of the leaf fragments as they occur, and then re-appreciate them when they repeat (in a new tempo/dynamic, etc...).  Another idea is to compare the juxtapositions of the leaves.  Since the leaves are chosen at random, some transitions would naturally work better than others.  Repeated listenings of different versions of KLAVIERSTÜCK XI would eventually make the leaves familiar, and these ideas of comparing returning leaves and leaf sequences would probably be easier.  Even if only a few leaves become familiar, their appearance could bring out these aspects to the listener.  In a live performance, it's easy to know the transitions between leaves since the pianist will look up at the score to choose the next fragment (hopefully).

           The use of random eye-contact does bring a few questions to mind, though.  As just mentioned, Stockhausen conceives of this piece as a single, vibrating molecule made up of aleatory sub-particles (randomly-chosen and articulated), but I think a performer would naturally have certain "non-random tendencies" after he/she has become familiar with all of the leaves.  Is it possible for a pianist to be truly random after becoming intimately familiar with the piece?  Or perhaps, Stockhausen expects sub-conscious factors and familiarity to affect the choices of leaves...  Interestingly, Lindsay Vickery has proposed (or maybe completed, at this writing) a software score display program (Decibel ScorePlayer) which I gather will do all of the choosing for you, getting rid of the eye-contact element and just randomly choosing the next leaf.  I assume the performer would have to be very familiar with the work to pull this off effectively.

           Personally, I would have preferred that Stockhausen had published a "Cologne Version" sequence, just to have a "director's cut" version of this piece.  MIKROPHONIE I and MOMENTE have such published realizations, and something like that here would have been interesting.  I suppose that since the Aloys Kontarsky and Ellen Corver versions were recorded under Stockhausen's supervision, these would be the closest to something like that.

      The KLAVIERSTÜCKE:
      KLAVIERSTÜCKE I–IV
      KLAVIERSTÜCK V
      KLAVIERSTÜCK VI
      KLAVIERSTÜCK VII
      KLAVIERSTÜCK VIII
      KLAVIERSTÜCK IX
      KLAVIERSTÜCK X
      KLAVIERSTÜCK XI
      KLAVIERSTÜCK XII (EXAMEN)
      KLAVIERSTÜCK XIII (LUZIFERs TRAUM)
      KLAVIERSTÜCK XIV (GEBURTSTAGS-FORMEL)
      KLAVIERSTÜCK XV (SYNTHI-FOU)
      KLAVIERSTÜCK XVI (w. Sound Scene 12)
      KLAVIERSTÜCK XVII (KOMET)
      KLAVIERSTÜCK XVIII (MITTWOCH-FORMEL)
      KLAVIERSTÜCK XIX (SONNTAGS-ABSCHIED)

      Links
      KLAVIERSTÜCKE I-XIV (Ellen Corver) Sound samples, tracks listings and CD ordering 
      Buy the Scores 
      KLAVIERSTÜCKE Wiki 
      Stockhausen on the KLAVIERSTÜCKE (1955,1957)
      "Clavier Music 1992", Stockhausen on Piano Music (1992)
      "The Translation of Rhythm into Pitch in Stockhausen's Klavierstück XI" (Stephen Truelove, Persp.of New Music Vol. 36.1)
      "Mobile Scores and Click-tracks: teaching old dogs" (2010) Lindsay Vickery
      KLAVIERSTÜCKE I-XI by Aloys Kontarsky (flac)