Perceptually Motivated 3D Diffuse Field Upmixing

This paper presents a novel 2D to 3D diffuse-field upmixing method developed based on two recent psychoacoustic studies on vertical stereophonic perception: Perceptual Band Allocation (PBA) and phantom image elevation. The PBA renders vertical image spread by allocating each sub-band signal to either lower or upper loudspeaker layer according to the desired vertical position of the band. Horizontally oriented phantom image is perceived above the listener when coherent signals are presented from side or rear loudspeakers, and this effect is most salient for frequency bands centered at 500 Hz and 8 kHz. The proposed upmixing method first splits input signals into sub-bands, each of which is then processed for controlling horizontal image spread (HIS) and the 'aboveness' of the image. The resulting signals are upmixed for enhancing vertical image spread (VIS) by PBA. Pilot listening tests conducted using pop, funk rock and classical sources suggest that the proposed method can produce greater HIS and VIS compared to decorrelation-based upmixing methods.