Design of equalization filter for non-linear distortion of the loudspeaker array with listener's movement

Abstract: The importance of the real-time virtual auditory environment is dependent on the fidelity of reproducing the sound. The loudspeaker array provided with its ideal response is suitable for the sound reproduction. However, there exists frequency and phase distortions in the loudspeaker response that cause audible artifacts at the listener's ears. Therefore, this non-ideal response of the loudspeaker is equalized by an equalization filter before their use in the immersive audio environment. The frequency response of the loudspeaker is dependent on the listener's position and hence equalization must be performed at each of their positions. Whereas, to measure the frequency response at all such position is troublesome. In this thesis, the frequency response of the loudspeakers is measured for selected listener's position with respect to the loudspeaker array. The frequency responses at the unmeasured positions are estimated using interpolation techniques. The equalization routine for the loudspeaker is performed in this thesis by considering the linear and non-linear distortions individually. The measured frequency response is simplified by the inverse-distance law. These simplified responses or the deviations are representing the non-linear distortions of the loudspeaker response. This deviation is equalized by the design of a mathematical model. This model also achieves the interpolation of the frequency response and ensures the equalization of the deviations at all potential position of the listener. Here, the mathematical model is designed as the former step to the linear equalization filter. The measurements and analysis in this thesis are focused to equalize 36 loudspeakers mounted at the horizontal plane of the 60-channel loudspeaker array and accounting for the listener's movement inside the array. The equalized deviations are statistically analyzed using ANOVA and the performance of the model parameters is evaluated.