The main goals for this study were to better understand what are the acoustic conditions physically within a symphony orchestra on concert hall stages, how these physical conditions affect the players and ultimately how to design venues suitable for symphony orchestras. This was investigated through questionnaire surveys and dialogue with musicians, scale and computer modelling and measurements of existing stages. The results from the orchestra collaborations indicate that the impressions of acoustic conditions are related to complex perceptual effects. When relating these effects to acoustic conditions, a narrow and high stage enclosure with the stage highly exposed to the main auditorium appears most beneficial. Existing methods for assessing the stage acoustically by use of omnidirectional transducers without the orchestra present were found to have only limited relevance to perceived conditions. New methods and objective architectural measures have been proposed. The architectural measures successfully discriminate the most preferred from the least preferred stages of purpose-built concert halls. The results from judgements of existing stages support the finding of a narrow and high stage enclosure with a highly exposed stage being most beneficial. How to improve the assessment of acoustic conditions on stage is discussed. Copies of the thesis written in English can be obtained from Jens Jo/rgen Dammerud. E-mail address: jjdamm@gmail.com. 4

On concert hall stages the sound traveling between players consists of the direct sound, a floor reflection and early reflections off players and objects on stage such as instruments and music stands. In smaller music ensembles, the acoustic communication between players is normally good. In larger ensembles, there is a similar situation for short distances between players. However for ensembles like a symphony orchestra, the number of players on stage results in large distances between some players with many other players sitting in between, which block the direct sound and floor reflection paths. This study investigates the sound levels on stage with and without a large orchestra present, in the absence of any stage enclosure. Sound levels within the octave bands 63-2000 Hz on an empty stage were studied analytically, while sound levels over the same frequency range with players present were investigated in a 1:25 scale model, both without and with risers on stage. The main results are presented in terms of the attenuation introduced by the orchestra, with linear models developed to describe behavior for the octave bands 500-2000 Hz.

At present the most common measures for assessing stage acoustic conditions on concert hall stages are the Support measures – STearly and STlate. These measures are based on monophonic omnidirectional responses obtained at 1 m from the sound source, on a stage without a full symphony orchestra (or similar group of people) present. Both objective and subjective studies have been conducted, the latter using questionnaires with several orchestras and dialogue with musicians. Objective studies involved measurements on real stages of the Support measures and other acoustic measures such as T, EDT, C80, G7–50, Ge ( G0–80) and Gl( G80–∞) as well as a set of proposed architectural measures. These have been complemented with analytical as well as scale and computer model investigations into sound behaviour on both empty and occupied concert stages. The major results from these studies are presented in this paper along with a discussion of alternative approaches for assessing stage acoustic conditions. One important result concerned the relevance of directions from which early reflections arrive regarding perceived ensemble conditions, an objective factor not assessed by the Support measures.