Parabolic Sound Concentrators

R. C. Coile

Parabolic sound concentrators have long been investigated for application to military antiaircraft location, radio broadcasting, and motion picture recording. Olson and Wolff, of the Radio Corporation of America, developed a combination horn-reflector concentrator in 1929. Obata and Yosida, of Tokyo University, published measurements of amplification in 1930. Hanson, of the National Broadcasting Company, described the use of parabolic reflectors in broadcasting in 1931. Dreher reported in 1931 on the use of microphone concentrators in motion picture production. Sato and Sasao published the results of tests on the sound fields of deep parabolic reflectors in 1932. — Rocard published an analysis of the theory of the amplification of the reflector-type parabola in 1932. Schneider of the Moscow Radio Center made amplification and directivity measurements in 1935 while studying the application of parabolic concentrators to Russian broadcasting and checked his amplification data with Rocard's theory. Gutin, in Leningrad, independently derived the theory of amplification and went on to analyze directivity in 1935. — This paper presents the pertinent historical background and reports on an experimental verification of the theoretical acoustical directivity of parabolic concentrators as well as further checks of the amplification theory. The sound fields inside parabolic reflectors have also been investigated experimentally with an agreement found with theoretical fields calculated by principles of geometrical optics.

Print ISSN
Published
1948-09
Content type
Original Research
DOI
10.5594/J11756