Toward orthogonal non-individualised head-related transfer functions for forward and backward directional sound: cluster analysis and an experimental study

• Published in: Ergonomics 2010-06, Vol.53 (6), p.767-781
• Main Authors: So, R. H.Y., Ngan, B., Horner, A., Braasch, J., Blauert, J., Leung, K. L.
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; Analysis of Variance; Applied physiology; Auditory Perception - physiology; binaural cues; Biological and medical sciences; Biomechanical Phenomena; cluster analyses; Cluster Analysis; Computer Simulation; Confusion; Ergonomics; Ergonomics. Work place. Occupational physiology; Experiments; Female; Head - physiology; Heat transfer; HRTFs; Human physiology applied to population studies and life conditions. Human ecophysiology; Humans; Male; Medical sciences; Movement; Posture; Simulation; Sound; sound localisation; Sound Localization - physiology; Space life sciences; Spectra; spectral cues; Statistics as Topic; Statistics, Nonparametric; Stimuli; Surround sound; Surveys and Questionnaires; Transfer functions; Young Adult
• ISSN: 0014-0139; 1366-5847
• DOI: 10.1080/00140131003675117

Individualised head-related transfer functions (HRTFs) have been shown to accurately simulate forward and backward directional sounds. This study explores directional simulation for non-individualised HRTFs by determining orthogonal HRTFs for listeners to choose between. Using spectral features previously shown to aid forward-backward differentiation, 196 non-individualised HRTFs were clustered into six orthogonal groups and the centre HRTF of each group was selected as representative. An experiment with 15 listeners was conducted to evaluate the benefits of choosing between six centre-front and six centre-back directional sounds rather than the single front/back sounds produced by MIT-KEMAR HRTFs. Sound localisation error was significantly reduced by 22% and 65% of listeners reduced their front-back confusion rates. The significant reduction was maintained when the number of HRTFs was reduced from six to five. This represents a preliminary success in bridging the gap between individual and non-individual HRTFs for applications such as spatial surround sound systems. Statement of Relevance:Due to different pinna shapes, directional sound stimuli generated by non-individualised HRTFs suffer from serious front-back confusion. The reported work demonstrates a way to reduce front-back confusion for centre-back sounds generated from non-individualised HRTFs.