The Perceptual Effect of Vertical Interchannel Decorrelation on Vertical Image Spread at Different Azimuth Positions

Two subjective experiments have been conducted to investigate the effect of vertical interchannel decorrelation on the perception of vertical image spread (VIS). Pairs of vertically arranged loudspeakers, one at ear level and another elevated by 30°, were positioned at 0°, ±30°, and ±110° azimuth to the listener. The first experiment compared octave-band pink noise stimuli, consisting of two decorrelation methods with three levels of interchannel cross-correlation (ICC), a coherent sample and a monophonic sample. The effect of vertical ICC on VIS perception was found to be most effective for frequencies around 500 Hz and above, with little effect at lower frequencies. The second experiment judged the absolute lower and upper boundaries of perceived VIS, using stimuli from the first experiment, showing a potential association between VIS and vertical localization.