On the Quality of Reverberation

Abstract

In observations and measurements on the acoustical properties of a number of rooms varying greatly in size, shape and decoration, features bearing on the quality of reverberation are noted. In addition to accepted requirements for reverberation times as a function of frequency, some additional factors seem desirable. When high-frequency reverberation times in a concert hall are greater relative to the midfrequency reverberation than normally found in concert halls, the acoustical conditions are universally judged as unsatisfactory. A specific example of this condition has recently been corrected in the Kulas Hall of the Cleveland Institute of Music. Other factors relate to directional characteristics. It is believed that highly isotropic reverberant sound is not pleasant, but confusing. This condition is greatly improved if the preponderance of the reverberant sound approaches the listener in the horizontal plane. When the reverberation time is long, its pleasing quality is enhanced if it is possible to make judgments of distance and direction by the binaural-hearing sense. This latter sensation, rather than a prolonged reverberation time, is probably the principal effect, giving rise to the familiar acoustical properties of large churches.