Typical data and cluster analysis on head-related transfer functions from Chinese subjects

Head-related transfer functions (HRTFs) vary with individuals. To obtain consistent results in binaural analysis, typical or representative HRTFs are needed. Moreover, matched or customized HRTFs are also needed to improve the localization performance in virtual auditory display (VAD). Based on a HRTF baseline database with 52 subjects, the present work derives the typical HRTFs of Chinese subjects and sets of matched HRTFs data for scientific researches and VAD applications. Similarities among the HRTF magnitudes of different subjects are first analyzed. Then the typical HRTFs are obtained by searching for the HRTFs of an individual that, in the sense of average, are most similar with the HRTFs of other individuals in the baseline database. Moreover, individualized cluster analysis is applied to the baseline database and the matched HRTFs are selected from the nearest cluster center. The results indicate that the magnitudes of typical HRTFs highly correlate with most of other 51 subjects in the database, exhibiting an average normalized cross-correlation coefficient of 0.888. In addition, cluster analysis indicates that HRTF magnitudes for most subjects can be classified into seven clusters and represented by the corresponding nearest cluster centers, with average normalized cross-correlation coefficient between the nearest cluster center and other subjects within the cluster exceeding 0.882. By comparing the similarity between the Chinese HRTFs and those of Western subjects, it is also proved that Chinese and Western HRTFs differ significantly on statistics, and therefore separately analyzing the similarity and cluster of Chinese HRTFs is necessary and reasonable. Psychoacoustic experiments validate that, the typical HRTFs yield reasonable virtual source localization performance and for four out of seven subjects, matched HRTFs selected from the nearest cluster center reduce the reversal and in-head-localization errors.