Customization Of Individualized Head-related Transfer Function Based On Headphone To Ear Canal Transfer Function Measurement

5.1channel surround sound has been widely used in digital TV, domestic soundreproduction etc. However, in-head-localization occurs if original5.1channel signals aredirectly reproduced via headphones. In order to obtain natural auditory perception, the methodof virtual auditory display, i.e., the algorithm of head-related transfer functions (HRTFs)processing has been used to synthesize the binaural sound signals in headphone reproductionof5.1channel surround sound. In addition, equalization to the binaural sound signals by theinverses of headphone-to-ear-anal transfer functions (HpTFs) is needed so as to eliminate thetransmission character from headphone to ear canal. Due to the individualized dependenceHRTFs, the perceived performances of headphone presentation with binaural synthesisdepend on the HRTFs used. Individualized HRTFs promise better performance. It is difficultor unpractical to measure the HRTFs of each listener, however. To address this problem, thepresent dissertation proposes an approach to customize individualized HRTFs, in whichindividualized HpTFs are measured and then matched HRTFs are selected from a baselineHRTFs/HPTFs database according the similarity and cluster of HRTFs/HpTFs. Thecustomized HRTFs are also adopted to improve headphone reproduction of5.1channelsurround.The HRTFs related to the loudspeaker directions in5.1channel surround sound weremeasured from20human subjects and KEMAR artificial head using blocked ear canaltechnique. The HpTFs of the same subjects with3types of circumaual headphones, includingAKG K702, Sennheiser HD250, Sennheiser HD650, were also measured using sametechnique and with15repetitions of each type headphone. Cluster analysis was applied to theindividualized HRTFs and HpTFs magnitudes within a frequency range of400Hz-12kHz. Theresults indicated that the individualized HpTFs of AKG K702headphone exhibit clusteringtendency similar to individualized HRTFs, and therefore the matched HRTFs of new subjectcan be selected from the clustering HRTFs in terms of HpTFs measurement.The HpTFs of AKG K702headphone were measured from eight new subjects and thecustomized HRTFs of six subjects were obtained. The performance of customized HRTFs inheadphone reproduction of5.1channel surround sound was evaluated. The results of psychoacoustic experiment indicated that customized HRTFs improve virtual sourcelocalization as compared with nonindividualized HRTFs measured from KEMAR artificialhead. Therefore the method for customizing HRTFs is validated and feasible.