A practical evaluation method of auditory source width in concert halls

Abstract

This paper investigates how to measure the degree of interaural cross correlation (ICC) as a physical measure of auditory source width (ASW), the just noticeable difference (jnd) of ASW and the estimation equation of ASW in degree for a music motif as a practical evaluation method of ASW in concert halls. Some physical measurements and psychological experiments show the following results.(1) ICC measured without Aweighting using a dummy head without ear simulators agree with spatial impression measured by Barron and Marshall which corresponds to ASW. It is termed DICC, in distinction from IACC measured with A-weighting.(2) Weber's law is applicable to the perception of ASW. The measured jnd becomes smaller as DICC becomes higher, and the Weber's ratio, ΔDICC/(1-DICC) is almost constant in the range from 0.2 to 0.3.(3) The equation and the chart to estimate ASW in degree are obtained as functions of DICC and the binaural summation of sound pressure level (BSPL). An increase of DICC by 0.1 causes a decrease of ASW by about 4° and an increase of BSPL by 1 dB causes an increase of ASW by about 1.6°. A decrease of DICC by 0.1 is equivalent to an increase of BSPL by 2.6 dB in ASW. © 1995, Acoustical Society of Japan. All rights reserved.