Under aleatoric (from Latin aleatorius " belonging to the players," alea " dice, risk, chance " ) is understood in music, art and literature, in the broadest sense, the use of non- systematic operations that result in unpredictable, random result. In music this chance operations can be applied both at the level of composition as well as the as the continuation -conceived level of interpretation and, for example, the type and number of instruments, the duration of the play, relate to the order of individual sections or tempo.
The adjective aleatorically was first used in a musical context, in 1954 under Werner Meyer- Eppler, who used the term as a statistical term: " A signal name is aleatory when its course is fixed in the rough and is determined by averaging descriptive statistical parameters, depends on individual but on chance. " Meyer- Eppler used the term" aleatoric " especially in the context of vibration-related events, a (electro acoustic ) compositional use he describes; as he speaks, for example, of the " aleatory modulation ".
Pierre Boulez and Karlheinz Stockhausen attacked the terminus aleatoric and used it at the Darmstadt Summer Courses 1957.
Boulez transferred the concept to the field of musical form and explained in his Darmstadt lecture Alea (1957 ) the opportunities to have involved the chance as a compositional device in composition and interpretation. Boulez sought a musical development, " in various stages, at different levels of composition, opportunities ' enter ' the leaves. The result is then a " series of aleatory events within a certain period, which would remain even indeterminate". The work [ must ] " offer a certain number of possible roads: Although the chance or the performer a certain margin is thus left to the authorship of the composer is, however, beyond question, as all authorized facilities are compositionally controlled and thus the chance" absorbed " is, namely by means of very precise arrangements, where chance plays the role of a switch setting, which occurs at the last moment. "
The noun aleatoric fell for the first time in connection with Stockhausen's Piano Piece XI (1956 ), whose parts are to be heard in random order, tempo, volume and shape are each mandatory stop at the end of the previous part. Hilmar Schatz wrote in 1957 about the piano piece XI: " This improvised acting, seemingly randomly resulting interpretation moment is in reality controlled, controlled by chance, called in the jargon aleatoric '. "
Stockhausen did not understand the aleatoric as limited to the musical term, but as a general principle that can play a role in various fields.
An outstanding exponent aleatoric works was John Cage, who used in his compositions since the 1950s random operations. An early example is the Concerto for Prepared Piano and Chamber Orchestra (1951 ), the orchestral parts are based among other things on Losentscheidungen by the Chinese oracle book I Ching and coin tosses. More random methods used in other compositions, Cage, directed for example to the texture of the paper currently used, astronomical atlases, mathematical methods and work with the computer.
Starting point for this is Cage's chance operations concept of music he - influenced by Zen Buddhism - in the late 1930s and the early 1940s developed. Accordingly, where the composer " let the sounds come to himself, rather than to exploit them for the expression of feelings, ideas, or ideas of order ". The musical material should be completely objective and not provided by the composer with an aesthetic sense: " The basic idea is that every thing it yourself is that its relations to other things quite naturally arise without forced abstraction of sides of a, artist '. "
Cage saw chance operations as a universal method to that could be applied to all areas of a composition and to any type of musical material, and by a composer who transgress against his own work, the course of which he did not know as a recipient. Cages determined by chance operations " experimental music " is therefore excluded by some authors from the Aleatorikbegriff. Evangelisti, for example, believes that between the accident as something unforeseeable and the aleatory as a " conscious process " is inseparable with manageable possibilities.
Cage himself distinguished between chance ( chance) and Indeterminacy ( indeterminacy ). This distinction is "manifestly (1952 ): The only game instruction for the three sentences is" in the composition 4'33 Tacet "; duration, number of performers and instrumentation are therefore arbitrary and arise " by chance ", for example, as in the First performance by throwing dice. , the non-intentional acoustic events that take place during certain stretches of time, by chance, however, are uncertain because they are in contrast to the random parameters, no selection from a group of known elements.
Overall, the forms of aleatory composition are considered to be very different. There are various gradations, from a mild form of indeterminacy and / or chance, to an almost complete freedom of interpretation in which most, if not all the musical characteristics are not fixed by the composer. To cope with the variable shape of a musical composition aleatory justice, the notation is often done as an ambiguous graph, for example, the ( coarse ) the expiration of the music specifies or encourages the artist to a free improvisation. Other ways of notation are the purely verbal description, such as in Stockhausen's From the Seven Days or special characters expanded notation. Combinations of various methods are possible.
Although the terms aleatory or aleatoric were only coined in the 1950s, but the history of music, the use of chance operations in the composition is no merit of new music: In the Middle Ages threw Christian monks four differently curved iron bars at random to create a beautiful melody receive. Even a Mozart attributed Musical dice game made use of chance and roll the dice together let the listener waltz beats any two dice.