146th Meeting of the Acoustical Society of America, Austin, TX, USA, 10.-14.11.2003.

Part IIb: Effects of hair, clothing and headgear on localization of three-dimensional sounds


Klaus A J Riederer
Laboratory of Acoustics and Audio Signal Processing
Helsinki University of Technology (HUT)
P.O. Box 3000, FIN-02015 HUT, Finland
Tel: +358 9 451 2494; Fax +358 9 460 224
Email: Klaus.Riederer@hut.fi, URL: http://www.hut.fi/~kar



Seven 20-25-year-old normal hearing (<=20 dBHL) native male-undergraduates listened twice to treatments of 85 virtual source locations in a large dark anechoic chamber. The 3-D-stimuli were anew-calculated white noise bursts, amplitude modulated (40 Hz sine), repeated after a pause (total duration 3*275=825 ms), HRTF-convolved and headphone-equalized (Sennheiser HD580). The HRTFs were measured from a Cortex dummy head wearing different it garments: 1=alpaca pullover only; 2=1+curly pony-tailed thick-hair+eye-glasses; 3=1+long thin-hair (ear-covering); 4=1+men’s trilby; 5=2+bicycle helmet+jacket [Riederer, J. Acoust. Soc. Am., this issue]. Perceived directions were signified by placing a tailored digitizer-stylus over an illuminated ball darkened after the response. Subjects did the experiments during three days, each consisting of a two-hour session of several randomized sets with multiple breaks. Azimuth and elevation errors were investigated separately in factorial within-subjects ANOVA showing strong dependence p(<=0.004) on all main effects and interactions (garment, elevation, azimuth). The grand mean errors were approx. 16-19º. Confused angles were retained around the ±90º-interaural axis and cos(elev)-weighting was applied to azimuth errors. The total front-back/back-front confusion rate was 18.38% and up-down/down-up 12.21%. The confusions (except left-right/right-left, 2.07%) and reaction times depended strongly on azimuth (main effect) and garment (interaction). [Work supported by Graduate School of Electronics, Telecommunication and Automation.]