COMPLETE REPRODUCING SYSTEMS 



311 



ORCHESTRA 



CONDUCTOR 



SET 



d] 



MICROPHONES 



There are two serious disadvantages to this ideal system in addition to 

 the requirement for a double channel. In the first place, a set of ear 

 phones which must be worn throughout the performance and would not 

 be tolerated by most persons, is required for each member of the audience. 

 Second, in sound motion pictures, each listener should be in the same 

 position relative to the screen as the dummy was relative to the original 

 set. Such a condition is obviously impossible of realization and, conse- 

 quently, those members of the audience who are somewhat removed from 

 the screen will recognize a binaural effect not in accord with their distances 

 from the scene. It appears, therefore, that the practical limitations of the 

 ideal system render it undesirable for commercial application. 



C. Auditory Perspective Reproduction ^^. — In the binaural reproducing 

 system the ears of the auditor are effec- 

 tively transferred to the original scene of 

 action. A system for effectively transfer- 

 ring the original sources of sound from the 

 studio to the theatre stage is shown 

 schematically in Fig. 12.19. The sound is 

 picked up by three microphones and am- 

 plified in separate channels, each channel 

 feeding a separate loud speaker. The 

 three loud speakers are arranged on the 

 stage in the same positions as the micro- 

 phones on the pickup stage. One of the 

 principal objections to the system is the 

 number of channels required. In the case 

 of sound motion picture reproduction three 

 separate sound tracks would be required. 

 Radio reproduction would require three 

 separate transmitters and channels. Some 

 laboratory tests have been made in which 

 two channels are used instead of three. 

 This arrangement is a distinct improve- 

 ment over a single channel system and 

 appears to have commercial possibilities in both sound motion picture ^^ 

 and radio reproduction. 



In addition to the objections that arise from the need of several channels. 



1 



STAGE 



l3i 



UD SPEAKERS 



THEATRE 



Fig. 12.19. Schematic arrange- 

 ment of the apparatus for the 

 reproduction of orchestral music 

 in auditory perspective. 



33 Fletcher, H., Jour. Soc. Mot. Fie. Eng., Vol. 22, No. 5, p. 314, 1934. 

 3* Maxfield, Colledge and Friebus, Jour. Soc. Mot. Pic. Eng., Vol. 30, No. 6, 

 p. 666, 1938. 



