System Adaptation* 



By E. H. BEDELL and IDEN KERNEY 



A communication system for the pick-up and reproduction in auditory 

 perspective of symphonic music must be designed prop)erly with respect to 

 the acoustics of the pick-up auditorium and the concert hall involved. The 

 reverberation times and sound distribution in the two auditoriums, the 

 location of the microphones and loud speakers, and the response-frequency 

 calibration of the system and its equalization are considered. These and 

 other important factors entering into the problem are treated in this paper. 



WHEN the effect of music or the intelUgibiHty of speech is spoiled 

 by bad acoustics in an auditorium, the audience is well aware 

 that acoustics do play a most important part in the appreciation of the 

 program. One may not be conscious of this fact when the acoustical 

 conditions are good, but a simple illustration will show that the effect 

 still is present. Thus, of the sound energy reaching a member of the 

 audience as much as 90 per cent may have been reflected one or more 

 times from the various surfaces of the room, and only 10 per cent 

 received directly from the source of the sound. 



In listening to reproduced sound in an auditorium or concert hall, 

 the effect of the room acoustics is perhaps even more important, for in 

 this case the audience does not see any one on the stage and must rely 

 entirely upon the auditory effect to create the illusion of the presence 

 there of an individual or a group. Imperfections in the reproduced 

 sound that are caused by defects in the acoustics of the auditorium 

 may destroy the illusion and be ascribed improperly to the reproducing 

 system itself. 



In some types of reproduced sound, radio broadcast for example, 

 where the reproduction normally takes place in a small room, the 

 attempt is made to create the illusion that the listener is present at the 

 source.^' 2 In the case considered here, however, where symphonic 

 music is reproduced in a large auditorium, the ideal is to create the 

 illusion that the orchestra is present in the auditorium with the 

 audience. Since the orchestra is playing in one large room and the 

 music is heard in another, the acoustical conditions prevailing in both 

 must be considered. 



* Sixth and final paper in the Symposium on Wire Transmission of Symphonic 

 Music and Its Reproduction in Auditory Perspective. Presented at Winter Con- 

 vention of A. I. E. E., New York City, Jan. 23-26, 1934. Published in Electrical 

 Engineering, January, 1934. 



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