儿童球幕电影厅的声学设计

圆形平面或穹形平顶存在着明显的声学缺陷，这种现象在半球形房间中尤为严重。一座具有这种形状的球幕电影厅的声学设计是在钢筋混凝土薄壳完成以后才提出来的，所以增加了工作难度。因此必需采用一些特殊声学处理，要求重量轻、吸声强、具有散射特性等以减少圆墙和圆顶的聚焦和爬行效应，同时还要控制大厅的混响时间。经过多种声学措施后，达到了满意的室内音质效果。     

声场的计算机模拟

本文首先评述两种主要的计算机模拟方法:Monte Carlo法和声线法;然后用本文发展的扩散反射声线法研究房间形状、吸声器分布以及吸声系数对混响的影响;最后以一个模拟教室为例,计算其混响时间,前80ms反射声的方向分布等声场参数,说明计算机模拟在房间声学中的应用。     

厅堂中混响时间测量的一些实际问题

本文根据多年来在一些大厅中进行混响时间测量(空场和满场)的经验,以及利用不同声源所积累的资料,分析了测量的误差.由于记录读数误差导致的混响时间的变异系数可控制在5％左右,而由于厅内声场不均匀性所引起的变异系数则在10％左右.至于利用不同声源所得结果之间的偏差则往往小于上述的误差范围,因此它们的差异并不显著.比较时所用声源有乐队、白噪声、啭音、发令枪声和气球的爆破声.本文还指出,在某些厅堂中测得的混响时间重复率较低,类似情况或更严重者(相差达50—100％)在文献中亦有报导,值得注意.因此,制订规范化的测量方法也就非常必要.为模拟厅堂满场条件的声学特性,曾利用棉衣代替观众进行了混响时间的比较性测量,结果基本上一致.     

一种基于最大似然的混响时间盲估计方法*

混响是室内声学中的重要现象,在室内设计与音频信号处理中都需要测量或估计混响时间。本文改进了一种基于最大似然估计的混响时间盲估计方法,即采用说话人在房间中自然说话时发出的混响语音信号来估计混响时间的方法。该方法首先确定语音衰减段的最优边界,其次计算该衰减段的两个额外参数,据此筛选出符合条件的语音段,最后将满足条件的语音段采用最大似然估计得到混响时间估计值。在五个不同混响时间条件下的仿真表明,与已有方法相比,改进方法估计的混响时间同真实混响时间的偏差更小,方差更低,估计准确性较高。     

听从声围绕：好的音乐厅声学要素

听从声围绕：好的音乐厅声学要素ＪｏｈｎＳ．ＢｒａｄｌｅｙａｎｄＧｉｌｂｅｒｔＡＳｏｕｌｏｄｒｅ正好在一百年前，Ｓａｂｉｎｅ对音乐厅声学特性的量化迈出了最先的一步，建立了他的预期房间混响时间的著名公式出。在此以后，对音乐厅声学各方面量化的努力相继而起。...     

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此处所介绍的厅堂声学计算机模型计算了房间和多功能厅的声学响应。这个模型是以房厅的三维表示为基础的。每个墙面都赋予一个吸声系数,并且分成更小的单元。首先计算了单元间影响系数所组成的矩阵。对于给定的声源,可以计算每个单元收到的能量,并由此定出房厅内任一点的声级,这样又能够算出     

日本新建两大厅堂项目

１东京国家剧院占地４４０００ｍ２;于１９９７年９月开幕．内有１８００座的歌剧院,１４５００ｍ３,满场混响时间１．５ｓ;１０３８座的小剧场,７２００ｍ３,满场混响时间１．１ｓ;１６３６座的音乐厅,１５３００ｍ３,满场混响时间１．９５ｓ．各厅尚有ＥＤＴ,ＢＲ,ｔ;ＩＡＣＣ;Ｃ８０和噪声等多项测量指标．该项工程于１９８５年开始建筑设计国际竞赛,日本ＴＡＫ设计事务所获奖．声学顾问由美国Ｂｅｒａｎｅｋ和ＴＡＫ联合进行．设计中利用了多种手段,前后化了７年时问,并写出多篇声学论文发表．２东京国际论坛一座当今最…     

关于声学比—混响时间—语言清晰度关系的实验与理论计算

以前有关室内声场中语言清晰度问题的研究,都仅涉及混响时间“T”对语言清晰度“S”的变化关系,至于同一个“T”而不同声学比“R”的影响考虑很少。本文专为对各个不同T的条件下,“R”对“S”的影响进行定量研究。得到清晰度S与混响时间T乘声学比R的归一化实验曲线,并用声学比-混响系数K_(rR)的形式表示为K_(rR)=1.0-0.22lg(TR)或S％=98.7-21.7lg(TR)。这个结果说明:混响场中的语言清晰度S与(TR)乘积的对数成反比。令人惊奇的是,这个实验所得的物理律的形式类似于Weber-Fechner定律,但要比它复杂得多。     

庭院空间的音质

中国传统戏场有不少是庭院式的。在这种顶面敞开的空间中,混响很少,声场基本上是非扩散的,故其声学性能与全封闭房间有很大不同。经典的室内声学例如赛宾混响公式在此不再适用。且由于缺失了大量来自顶面的反射声,使反射声序列的精细结构有很大变化,在仅仅表征声音衰变速率的混响时间参量中却反应不出来。致使虽具有与封闭房间相同3D混响时间的庭院空间中,其混响感可能明显不同。本文分析了庭院空间内声场的若干特征,对庭院式戏场音质作了初步探讨。     

电影对白录音棚的声学设计

本文讨论了录音棚的声学设计。研究了穿孔板吸声结构,玻璃棉毡,胶合板半圆柱,可变吸收的板和转动柱体。建成了电影录音棚,获得很好的效果,在125Hz到4000Hz范围内混响时间不随频率变化。当打开或关上全部吸声板和柱体时,混响时间分别为0.6秒和1.0秒。提供了高度的声扩散,理想的清晰度和丰满度,并且便于传声器的放置。     

Sound strength and reverberation time in small concert halls

Sound strength and reverberation time measurements have been carried out in six small concert halls in Cambridge, UK. The sound strength G is a measure of the physical sound level in a concert hall and is closely related to the subjective sensation of loudness. It compares integrated impulse responses at a point in the measured room with that measured at ten metres distance in the free field.The aim of the measurements is to investigate the acoustic characteristics of the halls concerning sound strength and reverberation time. Furthermore the effect of the variable acoustics in the halls on these parameters is discussed in this paper. Especially for bigger ensembles it is often desirable to reduce the sound level in a small concert hall. The measurement results show that for a fixed hall volume, this can primarily be achieved by decreasing the reverberation time in the hall. However, with regard to the sound quality of a hall and the recommended reverberation times for chamber music, reverberation time cannot be reduced by an arbitrary extent. Therefore reverberation time and strength have to be balanced very carefully in order to obtain sufficient reverberation whilst at the same time avoiding excessive loudness. Finally the measured strength levels are compared to values derived from traditional and revised theory [Barron M, Lee L-J. Energy relations in concert auditoriums. J Acoust Soc Am 1988;84(2):618-28] on strength calculations in order to assess the accuracy of the theory for small chamber music halls. Possible reasons for the low measured strength levels observed are discussed with reference to related design features and objective acoustic parameters.     

Influence of absorption properties of materials on the accuracy of simulated acoustical measures in 1:10 scale model test

This study investigated the absorption characteristics of materials in a multi-purpose hall using computer models, 1:10 scale model and actual hall measurements of Gimhae Arts Hall (GAH), in order to predict and evaluate the acoustical characteristics. The elements of this scale model, such as reflecting walls, seats, audience, and absorption banners, were made with materials selected according to their absorption coefficients, measured in a 1:10 scale model reverberation chamber. After the real hall was completed, in situ acoustical measurements were conducted in the GAH and compared with those of the scale model hall. Comparison of these measurements showed that the delay time of the major reflections in the scale model hall was similar to that of the real hall. However, the reverberation time especially at low frequencies showed a difference between the scale model hall and the real hall measurements. The results of computer simulations for both scale model and actual hall showed that the absorption of seats and audience, the structural detail of the reflecting walls with different thickness and air spaces, and the duct facilities in the open-type ceiling are the major differences. It was confirmed that there are more complicated absorption characteristics in the scale model design of a multi-purpose hall than a concert hall.     

Measurement of sound absorption coefficients of flat surfaces in a workshop

To improve the acoustic treatment of facings and provide appropriate solutions for noise control at workplace, it is necessary to develop methods of acoustic characterization of the walls in industrial halls. Sound absorption coefficient measurement in industrial rooms is however quite a difficult task because of the partially reverberant conditions. This work describes the measurement of the sound absorption coefficient of flat panels subject to small angle sound incidence, in an industrial hall using an experimental device equipped with an acoustic array. The directivity of this array has been optimized so that the major part of the received acoustic energy would come from one portion only of the investigated facing, this, in turn attenuating the reflected beams due to the reverberation. This new device includes an impulse sound source targeting the panels. The present article focuses mainly on the sound source design and implementation. It also describes some sound absorption measurements carried in a semi-anechoic chamber and in an industrial hall in order to examine the performance of the device. Sound absorption coefficients of several standard liners obtained through this device have been compared to those resulted from the two microphone technique.     

中国筝的声功率级测试

筝是中国古老的弹弦乐器。但迄今为止,对其声功率级一直未进行科学的测定。本文在一混响室内根据ISO及GB标准,对二十一弦筝的声功率级进行了首次测定。两位资深乐师在混响室内分别演奏各自的乐器,通过围绕乐师和乐器布置的四通道测试设备,对筝所辐射的声功率级和动态范围进行测定。测试结果表明,中国筝在以不同力度演奏单音、音阶和乐曲时所辐射的声功率级及其频率特性均有所不同。考虑到乐器演奏音阶时所辐射的声功率级及其动态范围与演奏乐曲时的声功率级接近,并且,音乐的空间感也大都在乐器以f力度演奏乐曲的强音标志乐段时最为显著,故此我们建议中国筝所辐射的声功率级用其以f力度演奏音阶时的平均声功率级表示。本文测试的两架中国筝以f力度演奏音阶时的平均声功率级为85.9dB。文中不仅首次公布了中国筝声功率级的测试结果,并且所介绍的测试方法对其它乐器声功率级测试也具有借鉴意义。民族乐器所辐射的声音性能的确定是民族音乐厅堂音质研究的基础。     

Acoustic characterization of on-stage performers in performing spaces

The influence of on-stage performers on the acoustic characteristics of performing spaces is significant because the musicians are absorptive and close to the sound source. However, the acoustic information of the musicians and their effect on absorption, scattering, and diffusion remain unclear. The acoustic characteristics of musicians were measured in a reverberation chamber and a semi-anechoic chamber while varying the type of clothes, the instruments, and seating density. The clothing worn showed a larger impact on the absorption per person, whereas the addition of cellos resulted in low-frequency absorption per person. The addition of cellos also increased the scattering and diffusion characteristics. Finally, the total absorption by the musicians under various conditions was analyzed in a concert hall using the simple Sabine equation where the influence of the musician’s instruments resulted in reverberation time of more than 0.1 s decrease with about 90 musicians on stage. However, the influences of additional musical instruments resulted in no significant difference in the reverberation time compared to the people alone. In addition, scattering due to the various conditions of orchestra such as the seating density and the addition of musical instrument was not a significant predictor of reverberation time.     

Abhängigkeit der grenzen zwischen brauchbarer und unbrauchbarer durchsichtigkeit von der art des musikmotives,der nachhallzeit und der nachhalleinsatzzeit

The clarity of music in a concert hall in an acoustic field with the same ‘Klarheitsmass C’ (clarity index) is not related to reverberation time. The ‘Klarheitsmass C’ is defined as the logarithm of the ratio of the energy of sound which arrives from first reflection (up to 80 ms) to the energy from the later reflections. This ratio is correlated to the clarity. The influence of the time of commencement of statistical decay in real rooms on the clarity may be disregarded. Much more significant is the style of the music. It is possible that a correction is required. Baroque music, e.g. Mozart, demands the highest clarity, so a ‘Klarheitsmass’ of $\text{C = 0 dB}$ may be acceptable, but music of the romantic period may require a clarity of $\text{C = ?3 dB to C = ?6 dB}$. Hearing is more tuned to clarity. When music requiring crispness is heard before music which is romantic in style, then a desire for clarity which is not so high is demanded when listening to a performance of the latter.     

Holographic measurement of reverberation time

A system employing the radio frequency holographic method for the measurement of the reverberation time of an acoustic chamber is proposed. This system has the advantage of supplying visible information on the diminishing intensity of the acoustic wave. A simple mathematical model has been taken to discuss the basic principles involved in the system. A possible experimental set-up for the measurement of the reverberation time is described in detail.     

厅堂声学一百周年(1895—1994)

本文介绍自Ｗ．Ｃ．Ｓａｂｉｎｅ以来１００年厅堂声学的发展简史，包括室内声学理论，音指标与评价，声学测试方法，缩尺模型技术，计算机仿真技术及厅堂设计的发展，现状及关于今后研究方向的前瞻。     

Acoustical design of the Tokyo Opera City (TOC) concert hall, Japan

The Tokyo Opera City concert hall seats 1632, volume 15 300 m3, and reverberation time, with audience and orchestra, 1.95 s. As part of the design process, measurements on CAD computer and 1:10 wooden models of the hall and full-sized materials samples were conducted over a 5-yr. period. The hall in plan is rectangular. The ceiling is a distorted pyramid, with its peak 28 m above the main floor and nearer the stage than the rear of the hall. This unique shape was analyzed on the models so that all interior surfaces combine to distribute sources on the stage uniformly over the seating areas and to yield optimum values for reverberation time (RT), early decay time (EDT), interaural cross-correlation coefficient (IACCE3), bass ratio (BR), initial-time-delay gap (ITDG), strength (G), and sound diffusion index (SDI) [for definitions see L. Beranek, Concert and Opera Halls: How They Sound (Acoustical Society of America, Woodbury, NY, 1996)]. On the long ceiling facing the stage, Schroeder QRD diffusers provide diffusion, eliminate a possible echo, and strengthen lateral reflections. Performers and critics judge the acoustics excellent.     

Acoustical design of the multi-purpose ‘Hjertnes’ hall in Sandefjord

‘Hjertnes’ is a typical multi-purpose hall primarily intended for concerts. A three-dimensional ray tracing computer program was used to provide a picture of the sound energy distribution on the audience area of the hall, various room shapes being investigated. This resulted in tilted side walls and a convex ceiling. Variable acoustics have been obtained through the use of movable ceiling absorbing and diffusing elements. In addition, a demountable orchestra enclosure has been constructed within the stagehouse. Control measurements of pulse response and reverberation time are reported.