Physical Factors, Symposium on Wire Transmission of Symphonic Music and Its Reproduction in Auditory Perspective

BILITY to localize the direction, and to form some judgment of the distance from a sound source under ordinary conditions of listening, are matters of common experience. Because of this faculty an audience, when listening directly to an orchestral production, senses the spatial relations of the instruments of the orchestra. This spatial character of the sounds gives to the music a sense of depth and of extensiveness, and for perfect reproduction should be preserved. In other words, the sounds should be reproduced in true auditory perspective. In the ordinary methods of reproduction, where only a single loud speaking system is used, the spatial character of the original sound is imperfectly preserved. Some of the depth properties of the original sound may be conveyed by such a system, 1 but the directional properties are lost because the audience tends to localize the sound as coming from the direction of a single source, the loud speaker. Ideally, there are two ways of reproducing sounds in true auditory perspective. One is binaural reproduction which aims to reproduce in a distant listener's ears, by means of head receivers, exact copies of the sound vibrations that would exist in his ears if he were listening directly. The other method, which was described in the first paper of this series, uses loud speakers and aims to reproduce in a distant hall an exact copy of the pattern of sound vibration that exists in the original hall. In the limit, an infinite number of microphones and loud speakers of infinitesimal dimensions would be needed.