18 – Solos

Introducing aspects of the contemporary solo repertoire : Composing with the Slonimsky Thesaurus : musical symmetry : approaches to good continuation : Interactions for Piano Left Hand : Studies in Movement for solo cello : introducing 2-D visualization : Array for solo violin – reinventing the Baroque suite : Sense of Placefor solo guitar – music generated from fingerings : use of library locations : collage : making spaces and musical punctuation using expression which set rules and conditions : Dreaming Aloud for solo guitar : Alexis Kirke’s Chromium 2 - a composition with Matlab.

For many composers making music for a solo instrument is bound up with the inspirational qualities and technical expertise of a known or admired performer. Musical literature is rich in such associations. Think of the works for solo cello of Benjamin Britten composed for Mistislav Rostropovich, or the Sonatas for solo viola by Hindemith (who played them himself), the wealth of music for the guitarist Julian Bream by Hans Werner Henze, the Sequenza series of fourteen solos by Luciano Berio composed between 1958 and 2002 for an elite body of influential performers, many of whom had already pushed the boundaries of solo performance before Berio’s rich imagination pushed them yet further.

The list above largely avoids music for solo piano because so much of the piano’s solo music aspires to the condition and grandeur of orchestral music, and is often subsequently orchestrated. This doesn’t mean music for solo piano won’t feature here, but it will be music that is very idiomatic to the solo instrument itself.

Furthermore, the initial list focuses on composers whose musical structures have favoured pitch and rhythm, whereas timbre, spectral harmony, noise, music theatre and complex rhythmics has, in solo compositions, enriched the medium. Consider the many fascinating solo works of Tristan Murail, Brian Ferneyhough, Richard Barratt, and Salvatore Sciarrino.

In this section works for solo violin, cello, guitar, and piano left hand have been selected. By and large these pieces celebrate that playfulness of the interaction of pitch and rhythm as well as the natural and resonant qualities of instruments; music that sounds well. The very constraints that writing for most solo instruments require have often been an inspiration and attraction in themselves.

If there is one common factor that links some of the music chosen to discuss here; it is the use of the Slonimksy Thesaurus. Three out of the five works use the Thesaurus as a ready-made source of structured and unified collections of pitches. These scales and musical patterns have a very particular symmetry in the organisation of tones and intervals that does not belong to the major / minor key system. The phenomenon of symmetrical patterning in tonality is something that emerged in the music of the late 19th century and can be heard in the music of Liszt, Scriabin, Stravinsky and Schoenberg. Think first of the symmetrical nature of octatonic and whole-tone scales. In the Thesaurus there is an intriguing ambiguity present in many of the patterns, which is one reason why jazz musicians have long been attracted by its possibilities and potential. The basic premise of such patterns is to divide the octave into symmetrical parts, for example the first patterns make the division into two tritones and then sequentially altered scales are derived within each tritone. Here’s an example of the initial Slonimsky patterns used throughout the Stages Tutorial of Opusmodus:

18-2Here is how the pitch series is extended by transposition using the intervals of the series. It is this kind of device that lies at the heart of that good continuation of material composing for solo instrument so often demands. The transposition sequence is accompanied by altering the rhythm with a function length-rest-weight that places one or two rests into different positions in each bar:

18-3What’s happening here is a kind of algorithmic improvisation. The precise nature of the rhythmic scheme is handed over to a function which delivers a possible solution. To try another solution change the random seed at the end of the second expression shown above. For another and more complex view of a composition using this initial Slonimsky pattern alongside a play of binary rhythmics look and listen to this Toccata, already featured in the section On Being Too Obvious. This takes such improvisation with transposition and rhythmic play still further.

18-4A Cypher ‘state’: the right hand portion of the interface showing
the opening ‘state’ for Nigel Morgan’s

Composing a work for piano left-hand poses an interesting challenge and one that invites the use of a Slonimsky series. In Interactions, the music ‘interacts’ with Robert Rowe’s Cypher MIDI system though the musical score had to be performable with or without the added technology requiring a computer and a MIDI keyboard. Five Interactions were created and all used the same model as a starting point:

18-5Using the same device as in the previous example from the Stages tutorial the Slonimsky ’motif’ is extended over three octaves:

18-6Now the process of replacing the ‘c’ pitches in the model with those from the Slonimksy series can begin. The score-file uses a function gen-random-keep to ‘keep’ or ‘protect’ particular pitches from change. In this example pitches in the first and third positions of each phrase are protected:

18-7This process is accompanied by a process-driven dynamic-scheme and added accents. To discover more about Interactions the score and score-file annotation are available on the composer’s web archive.

18-8The third solo piece featuring a sequential series of patterns from the Slonimsky Thesaurus is a collection of Studies in Movement for solo violoncello. The composer’s introduction states that the music ’favours lightness, speed and agility, and that dance-like fleet-of-footness found in the best Baroque performance practice, and notably in the dance movements of the six Cello Suites of J.S.Bach.’ Just as in Interactions this score makes use of generative devices that enable that ‘good continuation’ to be achieved with very little source material.

In the first study Continuum all the patterns of the sequential series 85 to 93 are featured, but coded separately in ascent and descent:

18-9With the patterns identified in ascent and descent it is possible to create further material by interpolating, for example, an ascending pattern with a descending pattern, as here with s 87u to s85d. Included within this interpolation is a palindrome with a randomised reflection as regards to length. An example might be (a b c d e d c).

18-10In the first and second bar two functions controls a velocity crescendo and a diminuendo followed by a crescendo respectively. The functions look like this:

18-11In the third bar articulation is modified by applying staccato. This can be applied in two ways: by an articulation ‘attribute’ or by defining the length of the pitches with a duration value half the defined note-length value.


18-13The first code example in OpusModusNotation brings all the parameters together in a single list. The attribute ‘leg’ (legato) is used to here to specify bowing. The second example shows how articulation is managed as a separate parameter in the Symbolic Composer application. In this approach the composer can select exactly the staccato duration required, and notice the duration value is able to loop inside the note-length value.

The second study is titled Arrested Motion. As the title suggests, phrases within this movement are broken up by pauses of indeterminate length. Following each pause the player is invited to change tempo, timbre and style of playing. The musical material is based on just the first pattern in the chosen series (Slonimsky 85). The intervals of this pattern are identified and then used to transpose the material sequentially – just as in the first two examples in this section. Then, the accumulated material is ‘cut-up’ into lists containing pairs of notes to create a large collection of self-similar patterns across a pitch continuum of two octaves. These are arranged to occupy a series of slots derived from the modulation of a sine wave by a ramp wave.


18-16The image below is taken from the Symbolic Composer Visualizer. The ’shape’ drawn by the data is also at the heart of the next composition to be discussed, Compass from Array for solo violin.


Array for solo violin is the first of a series of works for solo instrument that seeks to reinvent the essence of the Baroque suite. The movements are retitled with names that still suggest something equivalent to the collection of dance movements that provided metre, tempo and expressive content. They are: Compass, Perpetual, Gestures, Stasis, Transformation, Song, Dance.

In the opening movement the use of a Visualizer helps create the pitch and rhythm structure:


The score excerpt above shows the whole of the first phrase and the beginning of the second in sequence of upward scales. In the excerpt below the predominantly ‘falling’ and final phrase is shown to create a series of widely spaced downward arpeggios.


These phrase structures are created by four expressions in which sine waves are modulated by ramp waves. The output begins as vectors and then converts to symbols (rather than pitches). With the tonality of the music set to the chromatic scale starting on a4 the compass ‘(a l) is a chromatic octave. The remaining compass dimensions are also of a chromatic octave starting on a4 (2 octaves and c#5 (2 octaves).

18-21The rhythm is also a by-product of the melodic phrases. The key functions creating note-lengths are get-fill and get-timing. The function get-fill counts repeated notes. Compare this output with the rhythm at the opening of the score:

18-22This output is then processed by get-timing set to the value of a 1/16:


Making 2-D visualizations of musical parameters offers a new way of conceptualisation. Such graphical tools as shown above can plot pitch, rhythms, duration, dynamics and orchestration and offer a host of different display paradigms. The composer can now view the interaction of multiple streams of parametric data, a perfect way to take in complex algorithmically-generated material.

In Array the visualization shown above was employed in the early stages of a project before precise pitches or rhythms were decided upon. Such a graphical representation can easily present a ‘rough idea’ or a general direction. It can also be invaluable for modelling gestures and relative densities of activity. Here’s another use of such graphical visualisation in viewing the scoring of an ensemble. 

18-2418-25The example uses the function gen-accumulate. This is how the function works:

18-26As the final example of music for solo instrument let’s see how working with integers derived from fingering patterns can create a unique compositional signature and solution. Sense of Place is an ambitious four-movement work, a kind of four seasons for solo guitar. In general the music is assembled from a collage of material, some generated from parametric experiment, some from distorted quotations from Bach’s 1st Cello Suite, some from direct quotation and arrangement from the Ludus Tonalis by Hindemith. This means that there is no single score-file that reflects a whole movement, more a collection of experiments with gestures and combinations of gestures and particular material which was then assembled and extended on a score writer.

The movement titled Autumn is probably the most ambitious and radical in its use of collage and computer-generated ordering. It brings together five score-files, four of which make consistent use of fingering patterns as a means to generate musical statements. In the first of these files patterns that involve ‘pull-off’ or downward liguados are collected into a library file.

18-27Unusual tonalities are created with integers to encompass and relate to the pitches possible on each of the six strings of the guitar:

18-28The fingering patterns are ‘picked’ from the library files like this:

18-29The first expression ‘lists’ a scale of symbols that match the integer tonalities. The bespoke function pick-4 randomly picks four adjacent symbols. The final expression ‘collects’ 12 different fingering patterns that are each associated with a 4-symbol group. Between each group a rest symbol (=) is interleaved. As the piece progresses triads and diads are introduced that are inserted into these lists of fingering patterns. To insert such material a function e-insert is used to carry a list of insertion points. 

18-30Here is the opening of the work which shows how these elements come together. Notice the scordatura which requires that the lower six strings are retuned.


One aspect of composing for solo instruments with script-based computation has proved particularly valuable, particularly when processing a stream of generated data. It is the ability to be able to set up conditions or rules that can make changes or additions to the generated stream. For example, when particular intervals or repeated notes occur, or at the beginning or end of a phrases. 

In earlier chapters the composition for solo guitar Dreaming Aloud has been featured for its use of collage and mosaic-like structures. In its opening movement a Slonimsky pattern (c4 g4 fs4 cs4) or in symbolic language (a h g n) mapped to the chromatic scale starting on C is transposed randomly 48 times across two octaves. This creates a continuous stream which, for musical and technical purposes, needs to be broken up. It’s as though the last sentence was presented thus: Thiscreatesacontinuousstreamwhichformusicaland technicalpurposesneedstobebrokenup. We break up such a stream of words with spaces and punctuation, because without these things the text is unintelligible. This is such a fundamental issue in computer-assisted composition, but one frequently bypassed by the over-enthusiastic composer who can so often be seduced by the profligacy of the generated stream. 

18-32Now for the expressions covering rules or conditions. Essentially the rule present here governs every instance of the downward interval of a semitone – and in every position in the chromatic scale. It’s for this reason the use of symbolic (alphabetic) notation can be so powerful, and it can be applied to any scale or tonality list.

18-33The function all-in has 3 parameters: begin end position.


There is a reason the score example doesn’t exactly line up with the symbolic output. In the process of composing the score-file was run several times changing the value of the random seed which governs the control of the computer’s random generator.

The guitar has proved an inviting instrument for composers working with script-based programming systems. In this respect a most effective score titled Chromium 2 by Alexis Kirke was developed using the software Matlab. Kirke says of his use of this software that it ‘is excellent at the plotting of functions. In this instance the mathematical concept of a function expresses dependence between two quantities, one of which is given (the independent variable, argument of the function, or its “input”) and the other produced (the dependent variable, value of the function, or “output”). A function associates a single output with every input element drawn from a fixed set, such as the real numbers. These functions aid the business of creating the improvising machine that is at the heart of this composing process. Matlab is also particularly good at the implementation of algorithms, lists of instructions that make use of functions to complete a set task.’ 


One factor that Alexis Kirke’s code for Chromium 2 reveals is the way the open-strings and natural harmonics of guitar are made to interact sympathetically with stopped notes, particularly chords. The six open strings act as markers or objects around which stopped notes can circulate. The result is a very ‘playable’ piece that sounds well. 

Links and References
Paul Hindemith – Ludus Tonalis
Alexis Kirke – Chromium 2
Nigel Morgan – Toccata, Studies in Movement, Array, Sense of Place,
Opusmodus – website
Symbolic Composer – website

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