Multichannel Level Alignment, Part V: The Effects of Reproduction Level, Reproduction Room, Step Size, and Symmetry
A number of factors have been investigated for subjective level alignment of multichannel systems. Results show that the reproduction level is not significant; that the reproduction room is not significant for the front channels but can be for the surround channels; that a step size of 0.25 dB is necessary/sufficient; and that level calibration is symmetrical for a symmetrical setup. The correct level alignment of multichannel reproduction systems is critical to the quality of the reproduction. This fifth paper, from a series that describes work carried out in the MEDUSA project, discusses the results of experiments employing the nine test signals discussed in paper one. The experiments were conducted in an ITU-R BS1116-compliant listening room using a symmetrical loudspeaker setup positioned symmetrically in the room. Six subjects participated using the method of adjustment (MOA) procedure. The influence of reproduction level, reproduction room, step size in the MOA procedure, and symmetry of the setup were investigated. The results show that there is a significant effect because of the reproduction level in general, but under certain specific circumstances, the influence will be significant. The reproduction room is not a significant factor for the front channel level adjustments, but it is for the surround channels. The results also show that a step size of 0.25 dB is necessary/sufficient for subjective level calibration. Finally, the results confirmed previous conclusions that the level calibration is symmetrical around the center line of a symmetrical setup.
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