HRTF Customization Technique to Implement in Virtual Audio

Abstract

The ability of humans to use sonic cues to estimate the spatial location of a sound source is of great practical and research importance. Although considerable efforts have been made over the past century to understand the basic mechanism of the human auditory system, the role of each pinna cavity on auditory localization remains unclear to this day. Recent advances in computational power and acoustic measurement techniques have made it possible to empirically measure, analyze, and synthesize the spectral cues that influence spatial hearing. However, the current 3-D sound technologies are unable to compensate for the difference in individual spectral cues to render a fully immersive sound field, and development of an effective method for HRTF (head-related transfer function) customization still remains the biggest and open problem for virtual audio synthesis. Besides changes in source direction, HRTFs are also known to depend on source distance in case the source lies in close proximity to the head. However, most HRTF databases accessible from the Web up to the present day contain HRTFs for distant sources only due to several technical challenges involved in the measurement of HRTFs for nearby sources like equalization of increasing interference from the loudspeaker as it is positioned closer to the ears. In this study, HRTFs for nearby sources (located within 1 m from the head center) were measured using a B&K HATS (Head And Torso Simulator) dummy head microphone system and a special acoustic point source in order to construct a database and analyze their characteristics influenced by the direction as well as the distance of the source with respect to the head center. To provide more realistic and immersive audio experiences when listening to music or viewing live airwave TVs using PMPs (portable media players) such as MP3 or DMB (digital multimedia broadcasting) players, most high quality PMPs are available with 3-D sound rendering capability based on HR...