Influence of Back Wall Reflections on Crosstalk Cancellation Systems with Directional Loudspeakers

Crosstalk Cancellation (CTC) is a sound-field control technology used to deliver binaural signals over loudspeakers. This study investigates the effect of back wall reflections – occurring when the loudspeakers are positioned between the listener and a reflective wall – on CTC performance as a function of various parameters, including the positions of the listener and loudspeakers relative to the wall, and the directivity of the loudspeakers. Reflections are modelled using the Image Source Method (ISM), which simulates the contribution of reflection by superimposing the pressure field of the loudspeaker array with that of a mirrored array source. The directivity of the loudspeakers is simulated using directivity filters obtained from an open-access database. This approach offers a more realistic acoustic simulation than traditional analytical models. CTC performance is evaluated in the time and frequency domains using Neumann KU 100 HRTFs and Tikhonov regularisation. The impact of reflections is also quantified with a proposed error metric based on the Frobenius norm of the crosstalk matrix, which supports the simulation findings.