Automatic Regularization Parameter for Headphone Transfer Function Inversion

A method is proposed for automatically regularizing the inversion of a headphone transfer function for headphone equalization. The method estimates the amount of regularization by comparing the measured response before and after half-octave smoothing. Therefore the regularization depends exclusively on the headphone response. The method combines the accuracy of the conventional regularized inverse method in inverting the measured response with the perceptual robustness of inversion using the smoothing method at the notch frequencies. A perceptual evaluation is carried out to confirm the efficacy of the proposed method for obtaining perceptually acceptable automatic regularization for equalizing headphones for binaural reproduction applications. The results show that the proposed method can produce perceptually better equalization than the regularized inverse method used with a fixed regularization factor or the complex smoothing method used with a half-octave smoothing window.