Some Applications of Time Delayed Signals in Acoustical Environment Control
Hugh S. Knowles · The Journal of the Acoustical Society of America · 1954
The quality of reinforced or reproduced speech and music can be enhanced in many instances by the use of supplementary loudspeakers which are supplied with suitably delayed and spectrally modified signals. This paper deals with the use of systems in which the spatial distribution of the loudspeakers and the temporal control of the electrical signal energy serve both to control the ratio of direct to reflected sound and smooth the statistical decay of the sound energy and alter the fine structure of the decay so that flutter and echo are reduced. High or low ratios of direct to reflected and delayed sound are used depending on whether speech or music is to be reproduced. Supplementary loudspeakers have also been used in outdoor music systems to provide an artificial acoustical environment which simulates an environment normally preferred for indoor listening. Preliminary reports on listener preferences on abnormal and relatively normal environmental effects are discussed. Some analytical and experimental aspects of the sound ray or geometric and the statistical approach are given.