Jens Jørgen Dammerud  

Stage Acoustics for Symphony Orchestras - Just Black Magic? Part I

Jens Jørgen Dammerud
August 29, 2019

Editor's Abstract (Click to Hide)

Most musicians have at least some interest in acoustics. After all making sound is our business. Some of us have even taken an acoustics course in school. I remember taking such a course. We learned about overtones, wave forms, decibels and the like. We also learned about concert hall and room acoustics. But what I have no recollection of ever learning is the acoustics on stage—what musicians hear as we perform. Pretty important and interesting stuff, since what we hear on stage is not what the audience hears. This important and overlooked subject was the subject of Jens Jørgen Dammerud's PhD dissertation and Polyphonic.org is proud to present some of the findings of his study here in two installments.

- Ramon Ricker

Contents:

- INTRODUCTION
- pg. 1
- RESULTS FROM STUDIES OF EXISTING STAGES - pg. 2
- ACOUSTICAL CONDITIONS IMPOSED BY A SYMPHONY ORCHESTRA - pg. 6


INTRODUCTION

One might claim that the acoustic design of concert halls has been associated with a certain amount of black magic. How we perceive and judge sound is not easy to reduce down to a small set of simple and valid measurable relations, for instance any relationships between the size and shape of a concert hall and the achievement of exciting concerts for both the performers and the audience. Research within auditorium acoustics and psycho acoustics during the last 50 years have documented certain relations that appear valid, but the focus of these investigations has been primarily on the conditions for the listeners, not the performers. Still there are many aspects of acoustic conditions that are not well documented with regard to how they are perceived and unsuccessful designs are not yet fully eliminated. The uncertainties that still remain have led to tendency of copying properties old venues that through experience have proved to be successful, instead of developing new designs never seen before.

From the mid ‘70s to the late ‘80s acoustic conditions for performers were investigated by different research groups. These investigations were groundbreaking at its time and contributed to a better understanding of acoustic conditions from the performers’ point of view. Some of these studies also led to a proposal of objective measures like Gade’s ST measures (see the Further Reading section for more details). The ST measures assess the total level of reflected sound returning back to a musician on stage. The total levels of the reflected sound are summed within certain time intervals where the direction of the arriving reflections is ignored. The ST measures have been the most used objective measure for stage acoustic conditions and is now part of the ISO standard ISO 3382-1:2009 for assessing the acoustic quality of enclosed spaces. After the late ‘80s there were about 15 years without any significant scientific studies looking into acoustic conditions for performers, while the acoustic researchers and consultants reported very varied success with the ST measures. Is it still difficult to draw any lines with confidence between objective description of the stage/venue and ensemble conditions for the orchestral musicians on stage?

In 2005 Mike Barron initiated a 3-year project entitled Improved stage acoustics for performers. This project founded the basis for the author’s PhD thesis working as a Research Officer on the project. The aim for this article is to present the results and concepts from this PhD thesis, which hopefully can contribute to demystify acoustics for performers and point towards new directions for design of stages and performance spaces for symphony orchestras. The main results are presented first. A major finding is that orchestral musicians appear to prefer narrow and high compared to wide and low stage enclosures. The mid section of this article investigates possible explanations for such a preference. If both acousticians and musicians are familiar with these results and the developed concepts it may contribute to a common basis and make it easier for these two groups to communicate and exchange ideas. For more background and references to work by others, please see the Further Reading section.

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