ABSTRACT. This lecture does not deal with concert situations but exclusively with recordings released on compact disc or vinyl.

In other words: in this lecture I will exclusively focus on the spatial information or the reverberation pattern of a recording room and the acoustic result when listening to the recordings.

There are many different treatises about space and music. The thematic areas could be:

- The positioning of the sound source in space - The movement of sound in space - The simulation of architectural spaces and their spatial information (reverberation) - The acoustic construction of virtual spaces, i.e. spaces that cannot be built architecturally (reverberation that does not exist in the real world)

As a composer and architect, Xenakis dealt intensively and groundbreakingly with all these facets.

In aesthetic and scientific issues, little or no attention has been paid to room information (reverberation pattern) in acoustic recordings. Not even in the case of (artificial) reverb in electroacoustic music.

The key experience for my questions were these recordings of the compositions of Iannis Xenakis, interpreted by members of the Arditti String Quartet:

Kottos Mikka Mikka S Embellie Ikhoor

The remarkable thing: They recorded it twice within only 9 years: in 1982 and 1991

A comparison of the two recordings shows a remarkable difference: not in the interpretation but in the technical recording procedures. In short: in the 1982 recording almost no spatial information can be heard, no reverberation pattern. This is actually a sacrilege of sound and balance engineering (Tonmeister), since this is never the case with acoustic recordings.

How can it be explained that the 1982 recording sounds almost as if it had been recorded in an anechoic room?

Xenakis was actively involved in the 1982 recording and pushed through to create this extreme dry acoustic for the result.

Within the lecture I will

- mention here my interviews with the Arditti String Quartet about the recordings. - give acoustic examples for a better understanding. - give a short excursion into standardized recording techniques. - give an outlook on how we perceive spaces.

After these examples with acoustic instruments, I will make an excursion to Xenakis Electroacoustic Music. Here I will show the following fact: the more independent Xenakis was from a public studio like GRM, the more he renounced reverberation pattern. This can be seen very clearly in the two compositions where he worked independently:

Gendy3 Mycènes Alpha

Both are completely without reverberation(in electroacoustic music mostly artificial reverb) So as not to confuse anything: I continue to speak only of the reverberation pattern on a recording, not of the stereophonic information, which is undoubtedly present.

Again: what moves Iannis Xenakis to do this? One of several answers could be: the radicality of his thinking shows up here as well. The self-evidence, in a certain respect the tradition, to hear reverberation pattern at every listening of a (recorded) piece of music is also broken by him: he partially avoids it and thus creates new aesthetic directions of view, more precisely listening strategies.

For this lecture I need a good HiFi Stereo System.