Okano Toshiyuki
Takenaka Research and Development Institute, Inzai, Chiba, Japan.
J Acoust Soc Am. 2002 Jan;111(1 Pt 1):217-29. doi: 10.1121/1.1426374.
In concert halls early reflections combine with the direct sound and with reverberation to determine the subjective rating of a room's acoustics. Of interest is how variations in the amplitudes of these early reflections are related to the subjectively just-noticeable differences (jnd) in several important acoustical parameters for their wide range encountered in existing halls. Investigated were four subjective parameters, apparent source width (ASW), loudness, intimacy and clarity, which are related to the physical measurements, [1-IACC(E3)], G, ITDG, and C80, defined mathematically in Beranek [Concert and Opera Halls: How They Sound (Acoustical Society of America, New York, 1996)]. Forty-eight types of sound fields were chosen in which to make variations in the amplitudes of early reflections and were reproduced electro-acoustically by multiple loudspeakers in an anechoic chamber. The results indicate that ASW and loudness are more sensitive to changes in the levels of early reflections, and were the primary parameters investigated. Although the number of subjects available with enough experience in listening classical music is limited and the measured jnd is an initial estimation, the jnd of [1-IACC(E3)] is measured as 0.065+/-0.015 in variations of sound field structures and the jnd of G was measured as 0.25+/-0.15 dB, which is consistent with the results of previous studies.
在音乐厅中，早期反射声与直达声以及混响声共同作用，决定了房间声学的主观评价。值得关注的是，在现有音乐厅中广泛存在的多种重要声学参数下，这些早期反射声的幅度变化与主观上刚刚可察觉的差异（jnd）之间存在怎样的关系。研究了四个主观参数，即表观声源宽度（ASW）、响度、亲切感和明晰度，它们与在贝纳克（《音乐厅与歌剧院：它们的声学效果》，美国声学学会，纽约，1996年）中数学定义的物理测量值[1 - IACC（E3）]、G、ITDG和C80相关。选择了48种声场类型来改变早期反射声的幅度，并在消声室中通过多个扬声器进行电声再现。结果表明，ASW和响度对早期反射声水平的变化更为敏感，是主要研究参数。尽管有足够古典音乐聆听经验的受试者数量有限，且测量得到的jnd只是初步估计，但在声场结构变化中，[1 - IACC（E3）]的jnd测量值为0.065±0.015，G的jnd测量值为0.25±0.15 dB，这与先前的研究结果一致。
