Plus-Minus (Stockhausen)

[5] The piece represents an extreme instance of the new, open type of composition Stockhausen was developing at the time, and evolved from a number of conversations with Mary Bauermeister in Siculiana and Palermo.

[9] When Stockhausen heard a tape of this performance, he was astonished that sounds he had usually avoided were being employed, exactly according to the score's specifications, to achieve a highly poetic quality.

Material is systematically accumulated and eroded, in a process resembling a game of chess, where central and secondary notes either expand and proliferate, or are reduced until they disappear.

[13] The note material is all derived from the prime and inverted forms of the following twelve-tone row:[14] The types wax or wane according to the prescribed plus and minus processes, up to a maximum value of +13, which can result in very long sounds.

[16] The openness of the score was itself seen at the end of the 20th century as a form of control, deterring all but the most committed musicians from undertaking performances.