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Multichannel Speaker Configuration

Most of the pieces in this concert are in multichannel format, and therefore sound should be spread around the audience from at least eight different sound sources or loudspeakers. The recorded material should be played on a multichannel recorder routed in a discrete fashion to a multichannel console with also at least eight different channels. No mixing or diffusion is required for most pieces. In order to perceive the dynamic and motion of sounds two configurations or options for speakers placement are suggested:

Following is figure 1 which illustrates the idea of the truncated pyramid sound space.

Figure 1: Perspective of Pyramidal Speaker Placement
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Please note that there are eight speakers, a bottom plane and a top plane. The listener is in between those two planes but also surrounded by walls or boundaries which in turn can also form four corners to obtain different sound object trajectories. In order to get the truncated pyramid shape panning or panoramic and if the concert room is symmetric, controls for the upper plane speakers should have a slightly lesser angle value than the bottom ones. In this way an illusion of tri dimensional motion might be perceived in the room. Of course since each individuals head related transfer function is different the effect cannot be guaranteed. Nevertheless this configuration has been proved optimal for compositions with eight channels. The sound moves side-wise in a 270 degrees pattern while at the same time can also be perceived with a height of plus or minus 90 degrees.

Figure 2 is a layout for a group of also eight speakers viewed from the top of the concert room or auditorium. This configuration is optimized for sound diffusion where motion in a two dimensional plane is much desired.

Figure 2: Top view of an Elliptic Speaker Placement
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The goal on this configuration is to obtain a 360 degree panoramic perception of a sound in motion. It is very effective but in order to preserve the reverberation nature of a composition some delay needs to be added to the speakers closer to the audience. In this figure the group of 3,4,5,6 needs some delay to compensate the distance of the other speakers. An important feature in this layout is the use of virtual semi circles or also circumferences of different radius given that we have a sound source of 360 degrees. This sort of effect is achieved by adjusting sound intensity of the different and desired groups of speakers. Panning in the mixing console should have the maximum angle amplitude for the group toward the left or toward the right.




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Up: CCRMA @ The Age of Noise Previous: CCRMA, Center for Research in Music

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