Perceptual Band Allocation (PBA) for the rendering of vertical image spread

A series of subjective experiments were conducted to investigate a novel vertical image rendering method named
‘Perceptual Band Allocation (PBA)’, using octave bands of pink noise with a vertical 2D reproduction setup with
main and height loudspeaker pairs. The perceived height of each octave band was first measured for the main and
height loudspeakers individually. Results suggested a significant difference between monophonic and stereophonic
images in the perceived relationship between frequency and height. Six different test conditions have been created
aiming for various degrees of vertical image spread, in such a way that each frequency band was mapped to either
the main or height loudspeaker layer based on the results from the localisation experiment. Multiple comparison
tests were conducted to grade the perceived magnitude of vertical image spread. It was generally found that various
degrees of vertical image spread could be rendered using different PBA schemes, but the perceived results did not
fully match predicted results based on the localisation results. Differences between the main and height loudspeaker
layers in the spectral weightings of ear-input signal at certain frequencies was identified as one of the factors that
influenced this result.