音乐厅音质设计进展述评

本文对近年来音乐厅音质设计中若干问题的进展作一述评。（1）在已建立的众多独立音质参量基础上，如何作出大厅综合评价，就需要考虑到它们的互动性和贡献权，方法学将成为关键。（2）空间感已确认由声源视在展宽度ASW和听者环绕感LEV组成，对于影响两者的诸多复杂因素有了较深入研究，这声场中的细节又将如何与大厅设计相联系亦备受关注。（3）听众及座椅吸声这个老问题有了新的研究成果，对于空、满场的声学关系已积累了更多资料，使大厅音质的估算更为精确可靠。（4）常说扩散对大厅音质很重要，但其主观效应仍然处于玄虚状态，一些新的主观试听实验结果还不足以说明问题。     

音乐厅音质综合评价

通过综合许多厅堂音质专家的意见，本文建议一个更为完整的评价厅堂音质的因子集和较为合理的隶属度函数以便用于音乐厅音质的模糊集综合评价。所建议的因子集包括混响时间ＲＴ，合奏强音乐段的平均声压级ＬｐＦ，侧向效率ＬＥ，早期衰减时间的频率特性｜ＥＤＴ（ｆ）｜，以及音乐厅中１０ｌｇＬＥ值的极差Ｖｍａｘ（１０ｌｇＬＥ）。本文通过一个实例来表明综合评价的具体过程。可看出将模糊集方法应用于音乐厅音质的综合评价是可行的，因为它可以在模糊评估的基础上给出一个定量的评价结果。     

音乐厅音质设计中响度评价参量的讨论

强感级(G,dB)是评价音乐厅音质设计中重要客观参量之一,它由厅内声级按标准声源的声功率级归一化得出。我们不仅考察厅内的总强感级G,还得分别考虑其早期声和后期声的G_早和G_后,因为它们的成因和主观效果是不同的。近年从主观试验结果中获得一个意外发现,即最低频段的G_低值与中频G_中值之比,将是决定厅内低音感的主要因素,而不是过去所说的低频和中频混响时间之比。10年前,人们认为环绕感LEV只由到达听者耳际的侧向声能所决定,如今则了解到后期总声能G_后这一因素也很重要。并提出由G和侧向比值LF来估算LFV的新公式,便于设计考虑。本文对音乐厅最佳G值作了讨论。近年的一个重要发现是,音乐厅内听者响度判断主要由混响声决定,或认为因视听综合心理效应使听者的响度判断与离舞台距离几乎无关,或两者兼具。后者涉及视觉信息输入影响听觉响度体验,即所谓多维感知综合效果的心理学问题。近年有人认为G参量不能直接反映音乐厅内听众听到的绝对声压级为由,提出以音乐片段中乐队齐奏强音标志段声级L_pf作为评价音乐厅响度的新物理指标。作者对此作了全面评析,说明其存在问题和不可行性。     

白瑞奈克教授论音乐厅音质参数

讨论了评价音乐厅音质问题。根据音乐界对各音乐厅的主观评论,把调查过的58个音乐厅排出次弟。提出6个可测量的客观音质参数,并得出主观排列与客观参数的关系。     

北京红塔礼堂的音质设计

北京红塔礼堂是一个以音乐演奏为主的多功能厅堂,可容纳2010名听众.有效容积7800m~3.建成于1978年.为了适应自然声演出的需要,同年作了音质改善和调试工作,经几年的使用表明,音质良好. 本文主要介绍在大型厅堂内实现自然声音乐演出的设计要求和具体措施. 对大厅的音质设计和评价也作了概要介绍.     

改建电影院观众厅的音质设计

本文是针对35mm普通胶片电影院改建为兼容70mm宽胶片豪华型影院,所遇到的声学问题进行探讨。 改建电影院观众厅,在有一些条件限制时,提出所确定的声学设计指标,及为达到这些指标所采取的声学处理措施。经完工后测试证明:只要音质设计所选用材料的声学数据与实际情况接近,计算与实测结果误差就较小。此外,还提出一些值得进一步探讨的问题,诸如音质设计指标、室内扩散等问题。     

《建筑厅堂音质设计》简介

建筑声学的理论和实践已有１００多年的历史．虽然对于要求高质量音乐演出的厅堂,仍然存在着需要进一步探讨的原理和处理技术,但总的来说,对于不同功能的厅堂,在声学要求上已有一系列音质设计的准则和方法．对于从事建筑设计的工程技术人员,却有时难以全面掌握音质设计的基础要求． 王季卿教授新著《建筑厅堂音质设计》一书（２００１年 １月由天津科技出版社出版）,全面论述了音质设计的原理和技术：既阐述了系统的基础理论,又介绍了最新的研究进展;既讲清了音质设计中的声学原理,又对各种功能的厅堂介绍了典型的设计实例,使设计…     

A group of objective acoustical criteria for concert halls

To establish a definite list of the most important objective criteria for concert halls is not easy, but it is suggested that a group of four or five criteria may be sufficient to characterise, in general, the ‘acoustics’ of a specific hall. Comparing various concert halls by means of their measured objective criteria indicates that a rather simple method of ranking is feasible.     

Distribution of selected monaural acoustical parameters in concert halls

Acoustical parameters calculated from impulse responses are often used to evaluate the characteristics of concert halls. Representative parameters are listed in the Annex of ISO 3382 and the methods of calculation and the minimum number of measurement positions are explained in detail. However, a method for selecting measurement positions is not discussed clearly, because there are wide variations in the characteristics of sound fields. This report provides basic data to solve this problem using spatial distribution characteristics of parameters in halls. Three large-scale measurement campaigns were conducted in which impulse responses were measured at 1427, 180, and 511 locations. Relatively large differences in the obtained parameters compared with well-known difference limens suggest that determining the distributions of parameter values is important. Contour maps are therefore used to display the distributions along with mean values.     

Nonexponential sound decay in concert halls

The paper presents acoustic measurement results for two concert halls in which nonexponential sound decay is observed. Quantitative estimates are given for how the obtained decay laws differ from exponential. Problems are discussed that arise when using reverberation time to assess the quality of room acoustics with nonexponential sound decay.     

Development of scattering surfaces for concert halls

The degree of diffusion, characterized by the “scattering coefficient” of surface materials, has been known to be one of the most important factors in determining the acoustical qualities of concert halls. Based on the suggested ISO method, which measures the random-incidence scattering coefficient of surfaces in a diffuse field, the scattering coefficients of different sizes and densities of wooden hemispheres and cubes were measured in model-scale reverberation rooms. The results show that hemispheres with a height of more than 15 cm have the highest average (500 Hz to 4 kHz) scattering coefficient. It was also found that the scattering coefficient becomes higher when the diffuser density reaches about 50% for hemispheres and 30% for cubes.     

Relation of acoustical parameters with and without audiences in concert halls and a simple method for simulating the occupied state

Five acoustical parameters-reverberation time RT, early decay time EDT, clarity C80, strength G, and interaural cross-correlation coefficient IACC-were measured using identical procedures with and without audiences in six concert and opera halls. Reverberation times without audiences were measured in 15 additional halls using the same measuring techniques as for the six halls above, but for full occupancy the data were taken from musical stop chords at symphonic concerts. This paper shows that in all halls (1) the occupied RT can be predicted from the unoccupied RT using a linear regression equation, y = a - b exp(x), within acceptable limits, at low- and mid-frequencies. It is also shown for the six halls that (2) occupied C80's are predicted accurately from unoccupied values by the newly proposed equation; (3) G's with and without audiences are highly correlated by a first degree linear regression equation; and (4) IACCs have nearly the same value in both occupied and unoccupied halls. As a separate subject, the successful use of a cloth covering for seats in a concert or opera hall to simulate the occupied condition has been developed.     

Audience noise in concert halls during musical performances

Noise generated by the audience during musical performances is audible and sometimes disturbing. In this study, an attempt to estimate such audience noise was carried out. From the recordings of performances in five performance spaces (four concert halls and one opera house), probability density functions of the sound pressure levels were obtained in octave bands, which were fitted with three Gaussian distribution curves. The Gaussian distribution curve with the lowest mean value corresponds to a mixture of the technical background noise and audience generated noise, which is named the mixed background noise. Finally, the audience noise distribution is extracted by energy subtraction of the technical background noise levels measured in an empty condition from the mixed background noise levels. As a single index, L(90) of the audience noise distribution is named the audience noise level. Empirical prediction models were made using the four orchestra concert halls, revealing that the audience noise level is significantly correlated with the technical background noise level. It is therefore concluded that a relaxation of the current background noise recommendations for concert halls is not recommended.