Theater Loudspeaker Design, Performance, and Measurement
Referring to the on-axis measurement out of doors and the correction factor obtained at the Academy Award Theater indoors, the listening tests with Motion Picture Research Council Test Reel ASTR-3 and current studio product verify the electrical-response curve needed for adequate bass response. Additional low-frequency rise was used to determine its effect. It was found that no appreciable equalization could be used. In the case of the high-frequency droop, the rate of attenuation for this particular loudspeaker system was determined to be optimum using a response curve which has been in use for many years with this type of diaphragm and horn construction. — The Motion Picture Research Council Bulletin on Standard Electrical Characteristics dated April 20, 1948, states: — “Although the standard electrical characteristics for the newer-type speaker systems are essentially the same as for the older-type systems, acoustical-response measurements and listening tests have shown that a substantial increase in response is being obtained at the higher frequencies with the newer systems. The increase in efficiency and extension of frequency range is desirable so that the theater may take advantage of the improvements that are continually raising the standard of quality of the release print.” — It has been found over the years that attempts to correct major irregularities in response by upward equalization yield sound distinctly inferior to that produced by a system which does not require this equalization. The outdoor free-field measurement technique described has supplied information in such a manner that improvements in design are indicated and then checked for results. Smoothness of response is constantly being sought and this tool definitely indicates the progress that is being obtained. — To our knowledge, this is the first time a standardized method of measuring theater loudspeakers has been conducted jointly by designers and users. The outcome of the tests described here demonstrates the practical value of concentrated action along this line.
- Print ISSN
- 0097-5834
- Published
- 1949-06
- Content type
- Original Research
- DOI
- 10.5594/J16527