ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

3aAA10. Relations between the apparent source width (ASW) of the sound field in a concert hall and its sound pressure level at low frequencies (GL), and its inter-aural cross correlation coefficient (IACC).

Toshiyuki Okano

Takayuki Hidaka

Takenaka Res. and Develop. Inst., 1-5, Ohtsuka, Inzai-machi, Inba-gun, Chiba, Japan, 270-13

Leo L. Beranek

975 Memorial Dr., Ste. 804, Cambridge, MA 02138

The influence of GL (amplifier gain the low-frequency range below 355 Hz) and IACC on ASW was determined by psychoacoustic experiments with simulated concert-hall sound fields using anechoic symphonic music presented to subjects by multiple loudspeakers. ``Equal ASW curves'' were determined for 1/1 octave band filtered source signals with mid-frequencies from 125 to 4000 Hz. The ASW's for the upper four bands are found to be equal for the same IACC and SPL band values, indicating equal importance of those bands in determining overall ASW's. Combinations of GL's and IACCE3's (average of IACC's in the 500, 1 and 2 kHz bands) for wide-band musical source signals were determined that produced the same ASW's. The early sound was comprised of 2 to 11 early ``reflections'' and judgments were made with and without later reverberation. It was found that both larger values of GL and smaller values of IACCE3 result in larger values of the subjectively determined ASW's. It is shown that GL and IACCE3 jointly are physical measures of spatial impression in a concert hall and that, combined, they cover the frequency range from low to high frequencies.