A Comparative Study on Karlheinz Stockhausen’s Klavierstück X

This exposition intends to be a comparative study of certain notable, technical, and aesthetic approaches embodied within two separate performances of Stockhausen’s “Klavierstück X.” Klavierstück is a work of nineteen piano pieces. In this case, I’m going to examine the “tenth” piece in two alternate iterations. The two performers, both from Germany, are Herbert Henck (born 28 July 1948), and Aloys Kontarsky (born 14 May 1931). In many ways, both pieces have strengths and weaknesses that are apparent to my ear. I hope that the difficulties and challenges of playing Stockhausen’s Klavierstück X will be emphasized here — for any individual interpretation would need to surmount serious technical and physical hurdles to even approach performing this piece of music. Approaching Stockhausen simply cannot be a rote exercise — it requires much-sustained dedication and commitment, not to mention, radical self-acceptance.

The German word “Klavierstück” means “piano pieces”. These pieces were initially written as four small works composed from February to June in 1952. He later planned to write twenty-one works, however, only nineteen were completed. These works range from less than thirty seconds to around thirty minutes. Klavierstück III was the shortest of these pieces. The longer works are Klavierstück VI, X, XIII, and XIX.

Klavierstück X was commissioned by Radio Bremen (Germany’s public radio and television broadcaster). Stockhausen started writing sketches of Klavierstück X in 1954. It took him seven years to complete this work (in 1961). Fredric Rzewski, a Polish pianist, gave the first performance in Palermo in 1962. This piece is about twenty-two to twenty-five minutes in length. It is advised to wear fingerless gloves when preparing and performing this work in order to use the palm of the hand to its best potential. The range of sound is increased when wearing these gloves. It was recommended to use gloves that (according to the composer) allow for the palm of the hand to slide over the keys with more ease. Also, this piece requires the performer not only to use the palm of his/her hand, but also the wrist, forearm, and entire arm, as well.

Listening to this work might seem overwhelming to an average listener due to its intense density. In the first few minutes, we hear heavy, crackling clusters that are interrupted by sudden short moments of stillness and dwindling resonance.

There is a great deal of information condensed into the beginning — a three-minute opening that seemingly contains the whole work, holographically — as opposed to the more traditional foreshadowing that usually opens piano pieces. The pianist is playing nonstop, uninterrupted notes and clusters. He or she is being overworked, testing their mental and physical limits. The remainder of the piece consists of alterations between activity and resonance or silence. From looking at the score and listening to the recordings, I recognized that Stockhausen has a recurring trend. He would write many notes into a specific passage with either full-stop rests or waning resonance which follow closely upon one another — creating a powerful pulsating cadence. This was a very intelligent way to compose for two reasons. First, the performer is granted a few seconds to regain their energy and prepare for what is to come. Second, the audience would not be so overwhelmed with ongoing notes to process. It is difficult to keep a listener’s attention sustained without punctuation.

For the first two and a half minutes, rising and falling lines are moving undeterred by the interference of resonance. It is a fluid and flexible introduction. In this excerpt, the music is always moving and unpredictable. Tone clusters rudely interrupt this moving figure before the climactic and repetitive high “F” at the fermata of the passage. After this, multiple dissonant and sonorous sounds are heard asynchronously. In particular, the fast and frequent use of glissandi stands out.

Stockhausen wrote specific symbols to demonstrate various types of clusters. He used vertical lines with a number above the staff to represent how many notes to depress. The various numeric combinations include: 3, 6, 10, 15, 21, 28, 36. In the example below, the first measure includes F natural, F sharp, and G. We can assume that the other clusters use all white and black keys in between the lowest and highest pitch. Some clusters written in this work entail using the forearm; sometimes, both palm and forearm are used simultaneously. At the end of some passages, Stockhausen makes use of the full range of the keyboard requiring the performer to depress notes down with both forearms at the same time. Below, is an example of how Stockhausen wrote clusters:

Figure 1.

Another essential dimension of Klavierstück X is the employment of resonance through the use of the pedal. Sometimes Stockhausen requires a quick release of the damper pedal to create a resonating sound. This effect is brought about by controlling the dampers on the piano. Normally, when a note is played with pedal the sound will continue until the felt underneath the damper falls down on that string, thus stopping the vibration. One technique used by Stockhausen that requires a great deal of control is the act of depressing a note (or more than one note), releasing it, and then immediately pressing the pedal down to hear its resonance, followed by releasing it, but only halfway.

Another type of resonance is obtained by slowly and silently depressing a few keys on the keyboard to release the string from the dampers without producing any sound. Aside from the notes that are being held down, the pianist should play other notes normally. When this is executed properly, we can hear the harmonics of the semi-muted strings. When heard by the audience, these interesting sounds force the listener to open their ears to a noise that seems as though it is coming from a distance far away like an approaching train. This was a new and innovative technique that had not yet become popular. With these two specific directions, Stockhausen is experimenting with the sound of resonance.

Another compositional and performance aspect of Klavierstück X is the use of “Micro-individuals”. In the image below, Stockhausen wrote two different dynamics between both hands. The term, micro-individuals, refers to the importance of each detail. This can include dynamics as well as articulation. When looking at the score, we can see that the composer put a great deal of effort into his writings. The notes and directions change so rapidly that the performer cannot reply on prediction at all. It takes a considerable amount of patience and discipline to take on a piece such as this. Practicing by repetition and gaining muscle memory is one of the most efficient ways to master Klavierstück X. In the example of the micro-individual below, we must observe three different dimensions.

Figure 2.

First off, the dynamic in the left hand is marked triple piano while the right hand is piano. Second, all notes are to be played staccato except for A sharp in the right hand. Lastly, we must calculate the number of notes to be depressed in the tone cluster for the left hand.

During the early 1900s, composers started to explode with new ideas and techniques, notation too began a whole new journey outwards. New ways to score and create musical sound emerged from the constraints of existing traditional conceptions of harmony, melody, theory and orchestral technique — artists of this time were giddy with a new, but paradoxical, sense of freedom — they saw themselves breaking out from the box of an outmoded and staid musical vocabulary, which they believed had been murdered by war and technology — in addition to old aesthetic values. Later on, in Stockhausen’s time, the dissatisfaction of yet another generation, this one even more disillusioned by a second world war — challenged the paradigm again — pushing the envelope further with regard to both form and content. The cataclysm from which Stockhausen emerged, so radically affected him that he decided to start from scratch, embracing modernity with irony and iconoclasm. His ideas were so novel, he had to keep revolutionizing his own methodology continuously. This included the “traditional” concept of the musical score. At the beginning of the piece, we do not see a time signature or any tempo marking. The fact that there are no measures gives the performer a sense of freedom or terror. However, in Stockhausen’s instructions, he mentions playing certain parts as fast as humanly possible which is so great a challenge. He embraced speed as it existed in the post-war world and reflected it back to the world, although still allowing each performer a different overall pulse since every pianist has his or her limit as to how fast they can play.

An important point to mention regarding the score of Klavierstück X is that Stockhausen sometimes used three staves vertically. This was done in order to facilitate reading an extremely dense score. If he had only used two staves the piece would be considerably more difficult to read. Upon viewing the score, we can also recognize that Stockhausen uses a highly innovative rhythmic notation. The composer uses two different methods to express time and tempo. One way is the use of horizontal and diagonal lines in the score. If a group of notes or chords are held together by a vertical line, then the performer should play as fast as possible. Also, a diagonal line pointing upwards means to accelerando. A diagonal line pointing downwards would represent a ritardando.

Figure 3.

Duration is notated with bold large stems above the staff which is the most legible notation throughout. For example, there is a half note in the second system with 11 stems before the next given duration. Therefore, these 11 notes (or chords/clusters) must be played in the time of a half note with ritardando added.

Figure 4.

One interesting technique used by Stockhausen is the absence of rest symbols. When looking at the score in its entirety, we notice that he does not use a single rest symbol. The moments assigned for resting, pausing or resonance, are indicated by empty staff lines — giving each performer fewer symbols to process. The pause durations are simply notated by large, bold rhythmic symbols which are also used for the notes.

Figure 5.

Knowing which hand to use is rather clear when trying to decipher the score. If the stem is pointing upwards from the horizontal line, then it is played with the right hand. The left hand should play all notes with downward pointing stems. One should also recognize the large vertical lines that symbolize note clusters. For very large clusters that cannot be played with the hand, the performer is instructed to use his or her forearm(s). Also, black and white vertical lines combined with horizontal lines represent glissandi.

Figure 6.

Also, there are various pedal markings notated by Stockhausen. The letter P with a horizontal line underneath means the performer should depress the right foot pedal down all the way. If there is a P with a horizontal line through the middle of the letter, the performer should depress the pedal down, just enough, so that the note would still be audible after letting go of the key. The amount of depression depends on where the note is on the keyboard. The pedal should be down halfway when playing in the middle register. The pedal should be one-third of the way down for notes in the lower register. For the higher register, the pedal should be two-thirds of the way down. Finally, the pedal should be all the way down for the highest register. If a P marking is notated with a dotted line below, then the left foot pedal should be used. The performer may use this pedal at other times when not written as well if desired.

Now, I would like to begin an examination of the differences in approach to Klavierstück X by two historically integral interpreters of the piece.

There are at least thirteen separate dimensions organized into seven-degree scales. (Henck 1980b).

According to Henck’s analysis below, it seems as though Stockhausen used the number “7” in a variety of ways. Throughout Klavierstück X, he used seven different types of dynamics. He also used 1-7 notes in all chords. There were also seven different combinations of notes for tone clusters. Here are the thirteen different dimensions below:

(1) characters of chords (1–7 notes)

(2) characters of clusters (3, 6, 10, 15, 21, 28, or 36 notes per cluster)

(3) global (or “basis”) durations (1, 2, 4, 8, 16, 32, 64 units)

(4) action/rest durations

(5) note values dividing the action durations (1 to 7 divisions)

(6) attack densities (a two-dimensional scale, or a 7×7 matrix)

(7) degrees of order/disorder

(8) dynamics (ppp, pp, p, mf, f, ff, fff)

(9) range (bandwidth)

(10) forms of motion

(11) sound-characteristic (chained clusters, repetitions, arpeggio, etc.)

(12) rests

(13) shaping sound by pedaling

Herbert Henck played the piece at a slower tempo completing the work in 25’:26”. I decided to use the images of sound waves to compare the two recordings. I felt that this is the most accurate way to be able to distinguish the differences between the two pianists. I applied audio normalization to the two recordings by using a software called adobe audition. After normalizing the sound waves, I was able to draw multiple conclusions. When taking a look at these graphs, the first obvious realization I had was that Kontarsky played at a more lively tempo than Henck.

Figure 7.

I also compared the range of dynamics between the two pianists. If you take a look at the graphs on the next page, it is clear that the dynamics were more contrasting in Kontarsky’s recording. Both graphs are an excerpt from the last few minutes of Klavierstück X.

Dynamic ranges during the last few minutes of the recordings:

Figure 8. Henck

Figure 9. Kontarsky

To compare these recordings further, Henck obtained better phrasing, although it sounded as if the notes blurred together into a more muffled sound. Aloys Kontarsky let the notes move ahead a bit more and completed the work in 22’:44”. There were more accurate dynamics in Kontarsky’s performance (especially in the micro-individual parts). Also, this performance was more exciting and achieved a wider range of dynamics. The graph below shows both sound waves of the recordings of Klavierstück X in their entirety.

Figure 10. Henck

Figure 11. Kontarsky

I also spent some time at the piano with the score and recordings at hand. I listened to both recordings many times to compare the accuracy of notes and dynamics. I checked all notes and techniques at the end of the second system of the second page. The chords before the last glissando, triple-piano glissando, clusters, as well as the chords in the bass were all inaccurate in Henck’s performance! In comparison, the performance by Kontarsky consisted of more accurate tones, dynamics, and duration. He also played with more clarity in general and there was a greater amount of brightness in his sound production.

I noticed that Henck also played some chords incorrectly within the third system of the piece. He did not play the chords accurately before the fermata with a high F. The chord directly after the fermata is marked “piano” — however, I was unable to hear the accuracy of these notes. Also, the last few chords at the end of the second page are not clear or accurate in the recording.

When observing the action vs. rest durations mentioned above, Henck was sometimes too slow for those passages that were marked “very fast” by Stockhausen. For example, the clusters on the second system were not played fast enough in my opinion. Kontarsky played these passages very fast although observing the accelerando markings. Additionally, in Kontarsky’s recording, I heard more changes in character between sections. Aesthetically, it is very important to engage the listener by showing different moods throughout this piece.

Overall Kontarsky sounded more clear in his playing. Each note stood out sounding bright and sharp. I believe this performer played the “micro-individuals” better because of his attack and use of dynamics. Also, he played the glissandi more accurately by not giving more importance to this extended technique than to the chords.

I preferred Aloys Kontarsky’s interpretation of Klavierstück X. It was a more exciting and exhilarating performance. The general mood and feeling of Stockhausen’s opening section is “agitato”. The listener hears a great deal of complexity due to an abundant amount of information during the first few minutes and before the first rest takes place. The performer is also being overloaded with so many cues and directions. Because the score is so dense and concentrated, it was slightly difficult to follow the music for the first time. Alternatively, it was somewhat easier to follow Kontarsky’s performance because of his careful attention to detail.

If I were a pianist planning to perform Klavierstück X, I would list all the different dimensions of the piece by studying the score in great detail. I would seldom practice the piece from beginning to end until feeling somewhat comfortable with all of the many positions and directions in the piece. It would be best to break apart each section and study one to two systems at a time. For each cluster, I would practice slowly to check that the lowest and highest notes are accurate. I would not have to worry so much about the notes in between the clusters since all notes should be depressed down (whether black or white). It is more important to be confident in the outer notes. Also, regarding glissandi; I would practice the beginning and ending very carefully to be sure that I am starting and stopping on the correct note.

For ease of visibility, I would enlarge the score being that there are so many small details to digest. Also, I would try to show a great range of dynamics as Kontarsky did. I would be sure to show the mood changes between sections. “In Klavierstück X, Stockhausen composed structures in a series of varying degrees of order and disorder, where greater order is connected with lower density and higher isolation of events. Over the course of the piece, there is a process of mediation between disorder and order. From a uniform initial state of great disorder, there emerges an increasing number of ever more concentrated figures. By the end, the figures become unified into a higher supra-ordinate Gestalt” (Stockhausen 1964, 106).

In the quote above, Stockhausen explained that we should consider this piece as a whole. This work is structured with ongoing contrasting sections of order and disorder. There is a great deal of disorder in the more highly dense sections wherein we hear many notes condensed in a short period of time. In the less dense sections, there are pauses of varying degrees in length. In my interpretation, Klavierstück X starts as an argument and then slowly resolves over the course of time. By the end of the work, we feel a sense of peace by contrast and we recognize that Stockhausen is not saying something, insomuch as he is pointing towards something. Whether this is something that can or cannot be said, written down, or conveyed through any sort of representation, I cannot determine. Stockhausen, I’m sure, himself encompassed this place — beyond peace and the noisy world, and he provided the courage and the vision to dare others to look in that singular direction that only he could heretofore see.


Fowler, M. (2011). Becoming the synthi-fou: Stockhausen and the new keyboardism. Tempo 65 (255), 2—8. Cambridge, UK: Cambridge University Press.

Henk, H. (1980). Karlheinz Stockhausen’s Klavierstück X: a contribution toward understanding serial techniques: history, theory, analysis, practice, documentation. (pp. 5—48). (Trans. D. Richards). (2nd ed.). Köln, Germany: Neuland Musikverlag Herbert Henck.

Mooney, J. (2013), ‘Stockhausen’s Klavierstücke in Leeds,’ oral presentation given at the Exploring Theatre and Music ‘Ephemera’ workshop, University of Leeds, UK, 17 May 2013. Retrieved from https://www.academia.edu/3555517/Stockhausen_s_Klavierst%C3%BCcke_in_Leeds

Stockhausen, K. (1967). Klavierstück X [score]. London, UK: Universal Edition.

Stockhausen, K., & Henck, H. (1986). Klavierstück X [Recorded digitally at Westdeutscher Rundfunk Köln, December 1985 and April 1986.], Klavierstück I-XI [CD]. Mainz, Germany: Wergo. (1996)

Stockhausen, K., & Kontarsky, A. (1965). Klavierstück X [Recorded at KGH, Winterthur, Switzerland, July 1 & 2, November 15-17, 1965], Klavierstück I-XI / Mikrophonie I & II [CD]. Austria: Sony Classical. (1967)

Figure 1. An illustration of how Stockhausen wrote clusters in Klavierstück X

Figure 2. An example of using “Micro-individuals” in Klavierstück X excerpted from Stockhausen, K. (1967). Klavierstück X [score]. London, UK: Universal Edition.

Figure 3. An example of Stockhausen’s method to express time and tempo in Klavierstück X excerpted from Stockhausen, K. (1967). Klavierstück X [score]. London, UK: Universal Edition.

Figure 4. An example of Stockhausen’s method to notate duration in Klavierstück X excerpted from Stockhausen, K. (1967). Klavierstück X [score]. London, UK: Universal Edition.

Figure 5. An example of Stockhausen’s method to notate pause in Klavierstück X excerpted from Stockhausen, K. (1967). Klavierstück X [score]. London, UK: Universal Edition.

Figure 6. An example of Stockhausen’s method to notate glissandi in Klavierstück X excerpted from Stockhausen, K. (1967). Klavierstück X [score]. London, UK: Universal Edition.

Figure 7. A graph comparing the tempos in which Kontarsky and Henck played Klavierstück X.

Figure 8. A graph illustrating the dynamic ranges during the last few minutes of the recording by Henck.

Figure 9. A graph illustrating the dynamic ranges during the last few minutes of the recording by Kontarsky.

Figure 10. A graph illustrating the sound wave of Henk’s recording of Klavierstück X in its entirety.

Figure 11. A graph illustrating the sound wave of Kontarsky’s recording of Klavierstück X in its entirety.