Research project information - University of Bath 2005 - 2008
Our research project on stage acoustics in concert halls commenced 1 August 2005.
All musicians rely on monitoring the sound they produce; they depend on acoustic support. When musicians play in groups, they also need to hear each other in order to be able to play in time together and balance how loudly they play. In musical terms one says they need to achieve 'ensemble'. Both for support and ensemble, sound needs to be reflected back to the performers. An overhead reflector above the stage is a typical component, for instance. Not only is the amount of sound reflected back important but also when it arrives and from which directions. This study aims to extend our understanding of what sound reflections musicians need to receive and how this can be achieved in concert halls. The study will be conducted with the help of orchestral musicians; the Bournemouth Symphony Orchestra have shown interest in working with us. From working with them and possibly other musicians as well, we hope to find out which halls they like and dislike. We will make physical acoustic measurements in these halls in order to discover which characteristics are important for performances by orchestras. We shall also be conducting tests with acoustic scale models to find out in more detail how concert hall stages work and to look at the different sorts of acoustic contribution that acoustic reflectors make. (Scale models allow us to study behaviour in miniature with good accuracy, particularly where diffraction occurs as with finite size reflectors; computer models, though less accurate, will also be used.) As a subsidiary study, we shall look at the large number of architectural plans available of concert halls round the world. We will use these for a geometrical study of existing stages to inform our more detailed study of British concert hall stages. In some ways the problems of stage acoustics may seem straightforward: large hard surfaces reflect sound according to simple laws of reflection and presumably the more sound reflected back to musicians the better. The study of concert hall stage acoustics is not new and its history goes back over 15 years. However the requirements for good stage acoustics are still only vague and the physics of reflections is complicated by diffraction behaviour. The Danish acoustician Gade has proposed a quantity that can be measured on stages, but while it is adequate to pick very good and very bad stages, it is not very accurate in between. We plan to find out more about how accurate Gade's support measure is, to find out how much sound musicians like to receive soon after it has left their instrument and to find out how much they value later sound reflected from surfaces further away. Their preferences will differ depending on which instrument they play. Once we have found what they prefer, the acoustic study of actual stages and the study the possible contributions of typical surfaces around stages will, we hope, result in new recommendations for good stage design. Of course, a concert hall stage must also be designed to be seen by the whole audience; this acts as a constraint on possible solutions. This study is novel in that it will use symphony concert conditions as its focus. Some work has been done by others looking at chamber music conditions. The study of the physical acoustic conditions on stage will be in much more depth than earlier research. We trust that this study will help to improve conditions for orchestral musicians and be valuable for concert hall managements and the acoustic consultants who advise them. The work will be presented at acoustics meetings and published in international journals.
The project is supported by EPSRC. Also see project information here.
Last updated: 24 February 2008 by Jens Jørgen Dammerud
