CHAPTER XII 



ARCHITECTURAL ACOUSTICS AND THE COLLECTION 

 AND DISPERSION OF SOUND 



12.1. Introduction. — The advent of sound reproducing systems has 

 changed the problems involving architectural acoustics. Before the intro- 

 duction of sound reproducing systems the major concern was the optimum 

 reverberation time and the proper geometrical configuration for the best 

 artistic effects in music and the maximum intelligibility of speech. By 

 means of sound reproducing systems speech can be rendered intelligible 

 where before it was either too weak to be heard above the general noise 

 level or too reverberant. Furthermore, these instruments have opened a 

 field for all manner of artistic effects never before possible. 



The theatres which suffer most from insufficient loudness are, of course, 

 the large enclosed theatre and the open air theatre. Sound reproducing 

 systems have opened new vistas in musical renditions both by reproduction 

 and re-enforcement. In certain instances the volume range of an orchestra 

 is inadequate for full artistic appeal or to utilize the full capabilities of the 

 hearing range. In these cases, means are required for augmenting the 

 intensity of the original sound. The systems for accomplishing this 

 objective are termed sound re-enforcing systems. 



The acoustic problems involving the reproduction of sound motion pic- 

 tures are quite unlike those of stage presentations. Reproduced sound 

 offers greater possibilities for obtaining the proper artistic effects by the 

 use of the following expedients: the use of incidental sound, a wide volume 

 range, the control of the reverberation or room characteristics and the 

 use of various sound effects. 



For large outdoor gatherings, such as state occasions, athletic events in 

 large stadiums and parks, sound reproducing systems are employed to 

 amplify the speaker's voice. 



In department stores, hotels, hospital's, schools and factories sound 

 reproducing systems are employed to transmit sound from a central point 

 to several independent rooms or stations. The systems for accomplishing 

 this objective have been termed general announce or call systems. 



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