Sternklang
Sternklang (Star Sound), is "park music for five groups" composed in 1971 by Karlheinz Stockhausen, and bears the work number 34 in his catalogue of compositions. The score is dedicated to his spouse, Mary Bauermeister, and a performance of the work lasts from two-and-a-half to three hours. History and concept. "Sternklang" is "park music", to be performed outdoors at night by 21 singers and/or instrumentalists divided into five groups, at widely separated locations. The sounds from each performer is separately amplified and projected over loudspeakers. "Sound runners" transport musical "models" from one group to another, while  a percussionist stationed at a central position helps synchronise the groups to common tempos at ten points in the piece. The piece has been described as "a twilight fantasy … an extended outdoor "Stimmung"". From a technical point of view, it tackles and solves the problem of coordinating independent harmonic groups. Although "Sternklang" was first conceived in 1969, it was only composed two years later, on a commission from Sender Freies Berlin. The first performance took place from 8:30 to 11:30pm on 5 June 1971 in the Englischer Garten of the Tiergarten, Berlin, near the Akademie der Künste. The performers were  the Collegium Vocale Köln, an expanded version of Stockhausen's touring ensemble, Hugh Davies and his group, The Gentle Fire from London, and Roger Smalley and Tim Souster's ensemble, Intermodulation, from Cambridge. About four thousand people attended the performance. Despite the unusually difficult performance requirements, there have been a number of subsequent performances: The two Bonn performances in 1980 had been planned for outdoor performance in the . The loudspeaker towers were scheduled to be set up in the park on 21 July, five days before the first performance, but by that time uninterrupted rain had been falling for a  week with no improvement in sight, so the decision was made to relocate the performance indoors, into the large auditorium of the Beethovenhalle. Stockhausen found that there were certain advantages to an indoor venue (better auditory contact among the performers, improved control of the just tuning of the harmonies, etc.), and so decided henceforth to authorise such performances and drew up special instructions for those conditions. In connection with this extension of performance practice Stockhausen decided also that even a single group out of the five specified in the score, or any combination of two to five groups may perform  freely selected excerpts from "Sternklang" in concert. Analysis. "Sternklang" creates a sense of "non-progressive or circular time by blurring complex relationships between pitch and rhythm based on the overtone series so that the structure is perceived as inexhaustible and thus appears static". The entire composition is based on five just-intoned harmonic sounds, each containing eight tones corresponding to the second through ninth partials of the overtone series. One of these tones in each chord is the E above middle C, tuned to 330 Hz. In the first chord this functions as the ninth partial, in the second chord  as the eighth partial, and so on to the fifth chord, where it is the fifth partial. Compositionally, the harmonic structure fluctuates between an extreme situation in which all five groups share the same chord and the opposite extreme where each group's chord is different. The rhythms, tone colours, and pitch intervals in the "models" are directly derived from star constellations observed in the sky and integrated as musical figures. The self-similarity of the time and pitch structures recalls the same composer's "Gruppen". Reception. At the Birmingham performance in 1992, the composer observed members of the audience : The overall response of the audience attending was described by another observer: