Higher-Order Stereophony

This work introduces a new theory for spatial audio recording and reproduction named Higher Order Stereophony. Through the use of the Taylor expansion, the technique accurately reproduces a sound field across a line that is orientated as the interaural axis of a listener, to attempt to recreate a set of desired binaural signals. The technique utilises loudspeaker amplitude panning, and is shown to encompass in its framework traditional Stereophony approaches such as the stereo sine law. Therefore, the technique expands Stereophony to higher orders and more loudspeakers, leading to a greater frequency range of accurate reproduction, in a similar manner to Higher Order Ambisonics. Higher Order Stereophony is shown to exhibit many similarities to Higher Order Ambisonics, and decoders to transition between the different sound field representations are derived. Higher Order Stereophony is also re-derived through a mode matching approach using a subset of spherical harmonics, those with degree index equal to zero only. The theoretical results are then validated through experimental measurements using various microphone arrays, considering the reproduced sound field across a single line and the reproduced spherical harmonic coefficients of the sound field.