Crosstalk Cancellation (CTC) is a technology that enables binaural audio reproduction over loudspeakers. The performance of a CTC system depends on multiple factors, including the geometry of the system, the characteristics of the loudspeakers, and the accuracy of the plant models used to design the CTC filters. While previous studies have examined some of these factors, the combined influence of loudspeaker directivity, array size and listener position has received limited attention. This study models loudspeakers with a spherical pole cap and uses interpolated Neumann KU 100 head-related transfer functions to generate accurate plant responses. CTC filters are computed using a Tikhonov-regularised pseudoinverse approach, and numerical simulations are performed to evaluate the impact of directivity, array geometry and listener orientation on CTC performance.
Spectral manipulation techniques offer a means of generating virtual sound-source elevation using horizontal loudspeakers. In comParison to cross-talk cancellation systems, these techniques can be more flexible and operate with even a single loudspeaker. However, the azimuthal stability of such approaches remains uncharacterised. This study evaluates the effectiveness of magnitude-based difference-spectrum filtering across lateral source positions, including intermediate positions rendered via amplitude panning, in loudspeaker-based reproduction. Direction-dependent filters derived from a mean HRTF magnitude response were applied over a horizontal-plane loudspeaker array, with physically elevated loudspeakers at matched azimuths serving as perceptual references. Perceived virtual elevation was quantified using the illusion ratio, a novel metric expressing virtual elevation shift as a proportion of the physical elevation shift at each azimuth. Virtual elevation reached approximately 50% of the physical elevation shift at central azimuths, decreasing significantly with lateral displacement, consistent with the reduced effectiveness of monaural spectral cues at lateral positions. A greater virtual elevation effect was observed for ipsilateral rather than contralateral source positions relative to the filter ear. Stimulus class did not significantly alter the azimuth-dependent structure of the effect. These results demonstrate that magnitude-based spectral elevation synthesis produces a measurable and robust elevation effect, most pronounced for central sources.
Extensive research has investigated the relative influence of interaural level and time differences (ILDs and ITDs) on the perceived position of aural stimuli. Historically, these cues have been compared using trading methods with stimuli presented over headphones. For the purpose of virtual audio applications using multichannel techniques, it is important to establish whether interaural cues are exploited similarly in such listening conditions. In this work, trading experiments were carried out both with stimuli presented over headphones and using a novel two-listener crosstalk cancellation array. Listener responses revealed similar trading behaviour in the crosstalk cancellation case when compared to the headphones case. At the lowest frequency tested, the measured trading behaviour is considered less reliable due to inaccuracies in reproduction of the target stimuli. With this exception, this work demonstrates that the general trends observed in historical ILD/ITD trading experiments also apply to stimuli presented using crosstalk cancellation, namely increased sensitivity to ILD and decreased sensitivity to ITD with increasing frequency.
