Subjective evaluation of auditory spatial imagery associated with decorrelated subwoofer signals
Martens, W. L.
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Although only a single subwoofer is typically used in two-channel and multichannel stereophonic sound reproduction, the use of two subwoofers enables manipulation of low-frequency interaural crosscorrelation (IACC), and this manipulation is particularly effective in producing variation in auditory spatial imagery. In order to document this variation objectively, a series of listening experiments were executed using a set of stimuli generated at five correlation values and presented in two reproduction modes. Both modes used two subwoofers, but in one of the reproduction modes identical signals were applied to the two subwoofers. The results of both exploratory and confirmatory listening experiments showed that the range of variation in both perceived auditory source width (ASW) and perceived auditory source distance (ASD) is reduced when negatively correlated signals are not reproduced at low frequencies. Global dissimilarity judgments were made for this set of ten stimuli in an exploratory study designed to reveal the salient perceptual dimensions of the stimuli. A subsequent confirmatory study employed a two-alternative forced-choice task in order to determine how identifiably different the stimuli were with respect to the two perceptual attributes revealed in the exploratory study, those two attributes being ASW and ASD. The implications of these findings for loudspeaker-based spatial auditory display are discussed.