Analysis And Investigation On Distance Localization Cues Of Near-Field Horizontal Sound Sources

Sound source distance perception is an important function of the human ear hearing system.Sound source distance perception is often affected by a combination of cues,including intensity,reverberation,and binaural cues.This work mainly analyzed and investigated the binaural cues and intensity that affect the near-field sound source distance localizationThe head-related transfer function(HRTF)has important applications in near-field virtual sound reproduction systems.Sound signals containing binaural cues can be generated by the HRTF.The HRTF is dependent on the location(both direction and distance)of the sound source and is also affected by individual anatomical parameters.Individualized HRTFs have been shown to affect the perception of sound direction,but have not been considered in distance perception.This work aims to discover,by means of psychoacoustic experiments for a virtual reproduction system through a pair of in-ear headphones,the effect of individualized HRTF on auditory distance perception for a nearby sound source.In this study,the individualized HRTF and KEMAR's HRTF were used to generate two different types of sound source signals with sound source distances between 0.2 and 1.0m and five lateral azimuths between 45? and 135? in the horizontal plane.Results of distance perception show that the variance of distance perception results among subjects is significant,the reason could be the stimuli are lack of dynamic cue and early reflections.However,via the analyses of mean slope of perceptual distance and correlation between the perceptual and real distance,we find that the individualized HRTF cue has insignificant influence on distance perception.The auditory distance localization result of static virtual reproduction system still has a gap with the actual results.Therefore,this work further conducted a psychoacoustic experiment by means of real sound source to investigate the ability of discriminating the sound source distance(near or far)in different directions under near-field conditions.Firstly,based on the self-designed and constructed sound source distance locating system,the distance resolution threshold of the two reference distances(0.5m,1.0m)is measured by the real sound source method under the conditions with or without constant level.The direction of the sound source covers the right half horizontal plane at intervals of 45?.The results show that the intensity cue obviously contributes to the discrimination of the relative distance,and the discrimination ability of the near-field sound source distance is also significantly different under different subjects and different sound source directions.The near-field sound source distance-perceived listening experiment results by the virtual sound reproduction and the real sound source method all show that the human ear hearing system has better distance perception for the lateral sound source than the median plane.This is because the binaural cues of the lateral source are more pronounced with distance,providing more distance localization information.