312 



ARCHITECTURAL ACOUSTICS 



STUDIO 

 ACOUSTICS or SET 



MICROPHONES 



AMPLIFIERS 



EQUALIZER 

 AND FILTERS 



ATTENUATOR 



AMPLIFIER 



MONITOR 



ACOUSTICS OF 

 MONITORING ROOM 



AMPLIFIER 



ATTENUATOR 



EQUALIZER 



OPTICAL SYSTEM 

 MODULATOR 

 NEGATIVE RECORD 



LABORATORY 



PROCESSING - PRINTING 



^%_^ NEGATIVE RECORD 



two other conditions tend to operate against the ideality of the system. 

 The first arises from the fact that the acoustical characteristics of the 

 theatre or auditorium are superimposed upon that of the set. Another 

 objection arises from the necessity of requiring that the sound sources 

 be spread far apart for the best effect. That means that the picture that 



is being reproduced should be 

 spread out to cover the same dis- 

 tance occupied by the sound 

 source; otherwise, the sound will 

 LOUD SPEAKER appear to come " off stage " in- 

 RECEivERs^ stead of from the picture. In 

 ATTENUATOR thc casc of tadio reproduction it 

 may be impossible to spread the 

 loud speakers sufficiently to 

 obtain good illustration of per- 

 spective. 



D. Sound Motion Picture Repro- 

 ducing System. — A complete sound 

 motion picture recording and re- 

 producing system is shown in Fig. 

 12.20. The first element is the 

 acoustics of the set. The factors 

 which influence the collection of 

 sound have been discussed in Sec. 

 12.3. The output of the micro- 

 phones is amplified and fed to 

 attenuators termed mixers. If 

 more than one microphone is used 

 as, for example, a soloist accom- 

 panying an orchestra, one micro- 

 phone for the singer and one for 

 the orchestra, the output of the 

 Fig. 12.20. Complete sound motion picture two may be adjusted for the 

 recording, processing and reproducing sys- proper balance. A low pass filter 



is usually used to reduce ground 

 noise above the upper limits of 

 reproduction. A high pass filter is used on speech with the lower limit 

 placed below the speech range. This latter expediency reduces low fre- 

 quency noises without impairing the speech quality. An equalizer is used 

 to accentuate the high frequencies to compensate for the film transfer loss 



POSITIVE RECORD 



THEATRE 



OPTICAL SYSTEM 

 POSITIVE RECORD 

 PHOTO CELL 

 AMPLIFIER 



EQUALIZER 

 AND FILTERS 



ATTENUATOR 



AMPLIFIER 



DIVIDING 

 NETWORK 



J r-1^^ MONITOR 

 -^^)lA— jjCJ LOUD 



SPEAKER 



STAGE LOUD SPEAKERS 

 ACOUSTICS OF THEATRE 



