Auditory-based smoothing for equalization of headphone-to-eardrum transfer function

Binaural headphone reproduction can be improved by equalization of headphone-to-eardrum transfer function (HETF) in an appropriate way. Direct inversion of HETF targeting at a flat frequency response cannot keep the peaks and valleys due to pinna and ear canal filtering that might help auditory perception. Moreover, direct inversion might induce annoying high Q peak values due to variability across listeners. Smoothing the HETF before direct inversion can avoid over equalization. Two auditory-based spectral smoothing methods were studied in this research. One is based on roex filtering that can simulate human auditory filtering in the basilar membrane, and the other is cepstral smoothing that can simulate the auditory perception characteristic of frequency resolution. Subjective experiments show that, in comparison to direct inversion, the two proposed methods can improve binaural headphone reproduction.