Objective evaluation of the sweet spot size in spatial sound reproduction using elevated loudspeakers

Abstract

In a previous study, three crosstalk cancellation techniques were evaluated and compared under different conditions. Least-squares approximations in the frequency and time domain were evaluated along with a method based on minimum-phase decomposition and a frequency independent delay. In general, the least-squares methods outperformed the method based on the minimum-phase decomposition. However, the evaluation was only done for the best-case scenario, where the transfer functions used to design the filters correspond to the listener's transfer functions and his/her location and orientation relative to the loudspeakers. This paper presents a follow-up evaluation of the performance of the three inversion techniques when the above mentioned conditions are relaxed. A setup to measure the sweet spot of different loudspeaker arrangements is described. The sweet spot was measured for 21 different loudspeaker configurations, including two- and four-channel setups. Lateral and frontal displacement were measured along with head rotations. The setups were evaluated at different elevation angles. The results suggest that when the loudspeakers are placed at elevated positions, a wider effective area is obtained. Additionally, the two-channel configurations showed to be more robust to head misalignments than the four-channel configurations.