Acoustics of large orchestral studios and concert halls

In order to establish design criteria for orchestral studios, which should be similar in performance to good concert halls, an extensive investigation has been in progress for many years. The effects of shape on the subjective acoustic qualities of a large enclosure are here examined with reference to a large number of concert halls and music studios, and a comparison is made, in particular, between concert halls of the traditional type and those which have been built during the last few decades. The former were generally of rectangular plan with walls and ceilings overlaid with ornamentation, whereas most recent designs have fan-shaped plans, reflecting canopies and comparatively smooth surfaces. Measurements of sound levels in different parts of concert halls during orchestral concerts show that, for a given sound level in the neighbourhood of the platform, the intensity at the back of the hall is no greater in halls with fan-shaped plans and reflectors than with the traditional rectangular shape. In the former case, the gain in the intensity of the first few reflections which results from the shape of the hall is offset by a reduced reverberant sound level. The authors conclude that the modern fashion of directing the early reflections towards the back of a concert hall, although it may improve the hearing of speech, has an adverse effect on the quality of music.