厅堂声学计算机模型的应用(英)

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,产由此定出房厅内任一点的声级,这样又能够算出（ａ）随距离变化的衰减,（ｂ）在任一平面上的声照度,和（ｃ）任一点所收到声能的接收指向性。可以算出房厅内任一被选定点的回波图,作     

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。     

厅堂声学缩尺模型五十二年

厅堂声学缩尺模型自1934年F.Spondok首先提出后,经过五十年代的初步应用时期和六、七十年代的极盛时期,在客观指标测量方面已基本达到了实用化,并在厅堂音质设计和研究中起到了巨大作用。本文对声学缩尺模型五十二年来的发展作了简要回顾。 本文参考了120多篇有关文献。     

厅堂扩声系统声学特性指标的建议

本文对厅堂扩声系统的最大粉红噪声声压级、传输频率特性、传声增益、声场不均匀度、失真等声学特性指标提出建议。它是以一些测量和使用效果的评价以及我国电声设备达到的使用特性为基础,还考虑了某些实验结果和国外达到的水平。当前对语言或演出用的扩声系统采用不同等级的声学特性指标是可取的。     

浮云吊顶厅堂混响过程的计算机分析

本文用计算机就以下因素对浮云式吊顶厅堂混响过程的影响作了定量分析:浮云上下空间的平均吸声系数比、体积比;浮云悬挂率及吊高。并对计算结果作了物理解释。     

声学国家标准介绍(Ⅵ)

本规范是为防止工业企业噪声的危害,保障职工的安全、健康和正常工作,保护环境,促进工业生产、建设的发展而制定的,适用于工业企业中新建、改建、扩     

声学国家标准介绍(Ⅰ)

国家标准局、国务院环境保护领导小组及国家计划委员会基本建设标准定额局等国家标准化主管部门,自1982年至今的几年中,已批准发布了由全国声学标准化技术委员会归口和审查通过的21个声学方面的国家标准,这些标准分别于1983年至1984年内开始实施.于1983年实施的12个国家标准已由中国标准出版社出版,各地新华书店技术标准门市部经售,其余的标准将于今年内陆续出版发行。为了使大家能及时了解这些标准的内容,本刊将自本期起,除了已作     

应用声学面临挑战

我国应用声学自三中全会以来取得可观的进展,为国民经济作出了积极的贡献. 举部分已经走出实验室进入应用的例:为海洋开发,研制出浅层剖面仪、深海地貌仪、多波束渔探仪;为语言保密通讯,研制出了几种声码器;为噪声控制,创造了微穿孔板吸声结构,大规模调查了城市噪声.在超声诊断方面,对显象诊断,积累了十分丰富的经验,研制出几种型号     

消声室声学技术的革新

半个多世纪以来,在室内建立自由声场,以尖劈为基本吸声构造,尖劈的长度基本定于所需的低频截止频率,建造尖劈占用大量体积的事实,似乎都是无需讨论或必须接受的。随着科学技术的发展,尖劈的长度要求(1/4波长),已经成为自由场室扩展低频截止频率的实际障碍。工业技术发展需要的自由场室,不仅有它特殊需要的低频下限,例如到50Hz,决定于它的环境条件,对于吸声构造又有相应的使用和维护方面的要求。本文从室内稳态声场的理论分析出发,提出扩展低频截止频率,以阻尼房间的简正振动为基本,界面的反射,应从在室内更接近球面声波的实际出发,建立自由声场的新思想。介绍了新开发的三种新型无纤维吸声构件和适应不同要求的两类自由场室。以一间已经建设成功的半自由场室为例,用复合板共振吸声器(CPA)和非对称构造吸声器(ASA)组合,吸声构件的厚度仅620cm,得到的自由场结果是:以1/3倍频程频带信号测试(这正是该室的使用测试信号),25Hz至80Hz,±2.5dB,100~16000Hz,±1.0dB,自由场范围9m至12m。以正弦信号测试,100Hz以上达到和频带噪声类似结果,100Hz以下至50Hz,自由场范围7m至9m。已建成50间以上类似的自由场室。     

全国厅堂音质研讨会在宁波召开

由中国声学学会环境声学分会和中国建筑学会建筑物理委员会、北京声学学会联合召开的全国厅堂音质研讨会于1989年11月1日至3日在浙江宁波举行。来自全国有关厅堂音质的研究和设计部门共23名代表,在会上宣讲了15篇厅堂音质的研究成果和设计经验文章,并重点研讨了以下四方面的问题: 1.国内外影剧场音质研究、设计的经验教训和音质指标; 2.新技术(方法)在厅堂音质研究、设计中的应用;     

On the behaviour of artificial head transfer system applied to acoustic evaluation researches for halls

The author has made tests for an artificial head transfer system whichis modelled on a Chinese male on its main physical behaviour such as frequencyresponses,frequency response differences between the front and the rear inci-dences,as will as on its important hearing behaviour such as localization,theperception of distance and room dimensions.The results verify that this kind ofartificial head transfer system can be used as one of effective tools of acousticevaluation researches for halls.     

锗单晶体变温霍尔效应实验数据的处理

采用微机控制和数字式数据采集系统,在变温环境下(77~420 K)对长为6.0 mm、宽为4.0 mm、厚为0.6 mm的锗样品薄片进行霍尔效应相关数据测量;通过对测量的霍尔电压作数据处理得到锗的霍尔系数RH(T)、电导率σ(T)和霍尔迁移率μH(T)与温度的依赖关系.该实验结果对学生理解半导体物理中的相关知识有重要意义.     

Justification of standardized level differences in rating of airborne sound insulation between dwellings

It has long been recognized that single-number quantities R′_w, D_nT,w or D_n,w result in different conclusions in objective rating of airborne sound insulation between dwellings. The difference between the values of these single-number quantities (SNQ), however, does not prove which of them describes the sound transmission between rooms most correctly. The main object of this article was to study which SNQ correspond best with transmitted living sound levels in buildings when reverberation time, volume of receiving room and sound insulation are taken into account. Data of 100 field measurements of airborne sound insulation were collected as well as 207 reverberation times of furnished rooms. The transmitted sound levels of living sounds were evaluated on the basis of known living sound spectra and measured level differences D. The results show that the SNQs standardized to reference reverberation time of 0.5 s lead in all cases to best correlation between the SNQs and the sound levels of transmitted living sounds. It was also checked whether the rating by D_nT,w would lead to higher transmitted sound levels of living sounds in larger rooms, but this was not detected. The use of D_nT,w makes rooms of different volumes equal in regard to required sound insulation between them. It is thus justified to replace R′_w with D_nT,w as the SNQ for rating the airborne sound insulation. Widening the frequency range down to 50 Hz or up to 5000 Hz did not give noteworthy improvement in the correlation.     

n一Si霍耳样品的制备及其性能参数测试

本文介绍ｎ－Ｓｉ霍耳样品的制备及其主要性能参数的测试原理与测试方法，并给出部分测试结果。     

The influence of absorption factors on the sensitivity of a virtual room’s sound field to scattering coefficients

Currently there is limited information on what scattering coefficients (SCs) to assign materials in geometrical room acoustic computer models. As a result, room modelers rely on general guidelines and intuition when assigning SCs. How sensitive is the predicted sound field to the user’s choice of scattering coefficients? The sound field’s sensitivity depends on its diffusivity (without SCs); the more diffuse the room’s sound field is, the less sensitive the virtual room is to the selection of SCs. In rooms with no fittings to diffuse sound energy, the sound field diffusivity is influenced by (1) room shape, (2) volume, (3) amount and (4) location of absorption, and (5) the choice of SCs. This investigation focuses only on the latter three factors. A rectangular room is modeled in ODEON v6.5 with 10 absorption schemes. These schemes vary in terms of the area of mirrored reflective surfaces, average absorption coefficient, and standard deviation of absorption. The amount of diffuse reflections at each room boundary as dictated by the SC is increased uniformly in each room. Changes in the room sound field, in particular in the reverberation time (T30), are examined at each step. Sound field diffusivity, and consequently a virtual room model’s sensitivity to SCs, is found to depend most on the area of mirrored reflective surfaces. Also, a proposed quantity called the Scattering Sensitivity Index appears to predict sound field diffusivity.     

一种测量金属线性膨胀系数的新方法

本文提出一种利用霍耳式位移传感器精确测量全局线膨胀系数的方法。     

Practical methods to define scattering coefficients in a room acoustics computer model

To predict acoustics of rooms using computer programs based on geometrical assumptions, it is important that scattering is included in the calculations. Therefore scattering is usually included in terms of scattering coefficients which are assigned to each surface telling the software the ratio between the part of the reflected energy which is not being reflected specularily and the total reflected energy. However the effective scattering coefficient of a surface depends not only on the roughness of the surface material indeed diffraction caused by limited dimensions of the surface as well as edge diffraction also causes scattering. For complex rooms it can be difficult to give a reasonable estimate to the magnitudes of scattering coefficients if these should also include diffraction and even if these frequency dependent coefficients could be obtained in the design phase, the processes of obtaining the data becomes quite time consuming thus increasing the cost of design. In this paper, practical methods to define scattering coefficients, which is based on an approach of modeling surface scattering and scattering caused by limited size of surface as well as edge diffraction are presented. The predicted and measured acoustic parameters in real rooms have been compared in order to verify the practical approaches recommended in the paper.     

Calculation of the absorption coefficients of optical materials by measuring the transmissivities and refractive indices

In this paper, a formula for accurate calculation of the absorption coefficient of optical material is deduced by the relationship of its transmissivity, refractive index and absorption coefficient. Because the values of transmissivity and refractive index of the optical material with a higher accuracy can be determined by the instruments or obtained directly from the references, the calculated results of the absorption coefficients with a higher accuracy is certified. The absorption coefficients of some optical materials are calculated with it, and the results are discussed.     

Electrical properties of simultaneously evaporated Sb-Te thin films

Thin films of Sb-Te of varying compositions have been deposited on glass substrates following the three temperature method. The dc conductivity (σ), Hall coefficient (R _H) and thermoelectric power (α) of annealed samples have been measured in the temperature range 300–470°K. Films exhibit metallic as well as semiconducting characteristics withp-type conductivity. The properties are found to be dependent on composition and thickness of the film. Paper presented at the Int. Conf. and Intensive Tutorial Course on Semiconductor Materials, New Delhi, India, December 8–16, 1988.