. Elements of acoustical engineering. Electro-acoustics; Sound. 294 ARCHITECTURAL ACOUSTICS the vertical coverage angle is very small, which means that practically any system will have a distribution angle sufficiently broad to supply the required vertical spread. However, for conservation of power the vertical spread of the loud speaker should correspond to the vertical angle subtended by the audience at the loud speaker. Since the distance of those nearest the loud speaker to those farthest removed (that is, considering the vertical angle only) is very nearly the same, the sound intensity fr
. Elements of acoustical engineering. Electro-acoustics; Sound. 294 ARCHITECTURAL ACOUSTICS the vertical coverage angle is very small, which means that practically any system will have a distribution angle sufficiently broad to supply the required vertical spread. However, for conservation of power the vertical spread of the loud speaker should correspond to the vertical angle subtended by the audience at the loud speaker. Since the distance of those nearest the loud speaker to those farthest removed (that is, considering the vertical angle only) is very nearly the same, the sound intensity from the loud speaker will be practically the same for all parts of the audience through any vertical plane and the use of compensation by means of the directional characteristics for change in distance in the vertical plane to obtain uniform response is not necessary. In the horizontal plane the spread of the loud \--i S S 8 8- FIELD LOUD SPEAKERS PLAN VIEW. ELEVATION VIEW Fig. Two arrangements of sound systems for addressing assemblages in large grand- stands. For the stadium on the left a large number of loud speakers are used, each loud speaker covering a small portion of the total area. For the ball park on the right, a single loud speaker cluster is used to supply the entire grandstand. speaker should correspond to the angle subtended by the stands at the loud speaker. Since the center line is farthest removed, a directional characteristic of the shape shown is necessary for obtaining the same sound level in all parts of the grandstand. To eliminate any difficulties due to feedback, a velocity microphone is used and oriented so that the plane of zero reception passes through the loud speaker system. The sound level required for public address work of the type considered above will be determined by the noise level of the maximum crowd. In general, it is not practical to employ a system with sufficient power to override the sound level during cheering, applause, etc. Ho
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