立体声影院声学问题初探

本文从立体声影院声学原理有关系的心理声学、电声学和建筑声学出发阐述了立体声影院声学设计方法和原则,并以重庆山城六声道宽银幕立体声影院声学设计、装修和实测结果作为例子进行了介绍。     

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。     

可用于户外的微穿孔吸声屏障通过产品鉴定

1996年12月12日由上海市轻工控股集团公司主持，对上海申华声学装备有限公司研究设计的SHP－W型微穿孔吸声屏障通过了产品鉴定，国家环保局、国家科委、上海市轻委、上海市环保局等领导以及北京、上海声学专家等90余人参加了会议。SHP－W型微穿孔共振吸声屏障根据马大献院士的微穿孔板吸声结构理论，采用了透明微穿也孔板和顶部扇形高效吸声体，结构新颖，声学性能优良，景观效果好，具有防雨水，防积尘，防反光等特点。该产品通过声学、力学等性能研究测试，完全满足高架道路使用要求，在上海延安路高架道路西段进行实际应用，取得了良好的效果，得到了用户的好评。鉴定会认为，将透明微穿孔吸声结构作为一种户外声屏障属国内外     

首都钢铁公司鸿儒厅的声学改建

首都钢铁公司鸿儒厅为一多用途大厅,主要用于宴会、会议和文艺演出,也可用来举行舞会及放映电影。大厅建成后,在开会、演出及放映电影时出现了语言清晰度差,音质不佳等问题,影响了大厅的使用。为此,声学工作者和建筑师密切配合、在不破坏大厅原有建筑环境的条件下,对大厅进行了声学改建,加装了吸声体、舞台反射板等声学构件。改建后的大厅语言清晰、音质良好,并使良好的听觉环境与良好的视觉环境达到了统一,受到了使用者的好评。     

全音节汉语语音识别系统的声学模型研究

本文在分析了汉语单音节发音的音节结构的基础上，定义了基于声韵母类的语音识别单元，从声学角度确定了用于汉语全音节识别系统的声学单元，并研究了这些声学单元的检测一致性及基于这些单元的识别系统的鲁棒性。文中还对大量的发音人的声母类发音的长度作了统计，给出了基于本文给出的分割算法和本文定义的声母单元下的声母长度预分类方法。通过在非特定人全音节汉语语音识别系统上的应用表明，本文定义的语音识别单元具有很高的检测一致性，建立在其上的识别，系统也具有很高的鲁棒性；文中给出的预选方法在最好的情况下，可以减少一半以上的运算量，而预选精度几乎达到１００％。     

面包的吸声性能

多孔材料因其优异的吸声性能在声学领域有深入的研究和广泛的应用。面包作为一种典型的多孔材料，其声学性能少有人关注。本文探究了面包制备工艺的对其声学性能的影响规律。本文主要通过研究酵母菌用量，发酵时间，厚度，面水比例，面筋强度的不同来探究对其吸声效率的影响。实验结果表明：实验用量酵母菌4g，发酵时间40min为宜，在此条件上，增加厚度，面水比例，面筋强度可以进一步增强吸收率，增强面包品质。     

多声学场景下端到端语音识别声学编码器的自适应

提出了一种面向多样化声学场景自适应设计声学编码器的方法 (SAE)。该方法通过学习不同声学场景下语音中包含的声学特征的差异,适应性地为端到端语音识别任务设计出合适的声学编码器。通过引入神经网络结构搜索技术,提高了编码器设计的有效性,从而改善了下游识别任务的性能。在Aishell-1、HKUST和SWBD三个常用的中英文数据集上的实验表明,通过所提场景自适应设计方法得到的声学编码器相比已有的声学编码器可以获得平均5%以上的错误率改善。所提方法是一种深入分析特定场景下语音特征、针对性设计高性能声学编码器的有效方法。     

SH型轻质高效装饰隔声门通过鉴定

1995年6月26日由上海市二轻局主持，国家环保局、上海市经委、市环保局有关领导和北京上海声学专家参加，对上海申华声学装备有限公司（上海红旗机筛厂）试制生产的SH型轻质高效装饰隔声门通过了生产鉴定．近年来，为满足电台、电视台、剧场、影院、宾馆会议室等厅堂音质工程的需要和高隔声量噪声控制工程的需要，国内试制了一些不同类型的隔声门，也从国外进口了一些隔声门．上海申华声学装备有限公司在有关专家教授的指导下，新开发了一种轻质高效装饰隔声门．总厚度为60mm，面质量为48kgm2，隔声指数大了42dB，与单位厚度单位面质量相…     

录音师声学进修班

在电影、广播、电视、唱片等部门,录音工作是一个十分重要的环节,它直接关系到艺术作品的质量.录音师声学进修班是以提高富有实际经验的录音师的声学基础知识为目的.其任务是着重介绍与录音工作有关的声学原理,从而提高学员的声学水平,以便在实际工作中发挥更大的作用.     

数字化声学测量技术──Ⅰ.概论

数字化是当今世界上声学测量技术的发展趋势，它采用微计算机和数字信号处理系统．数字化声学测量的主要优点是：1．精确度高，动态范围大2．性能稳定，可靠3．可实现许多模拟仪器设备不能完成的复杂功能4．使用灵活方便5．优异的性能价格比．本文综合介绍了数字化声学测量技术的这些优越性，同时还介绍了一种实际使用的数字化声学测量系统的组成和工作原理，以及它的主要测量分析功能．本文可为涉及声学测量的部门和单位在选择仪器设备时提供参考．     

中国传统庭院戏场若干声学特征

中国传统戏场在世界建筑史中别具一格,它与现代剧院迥然不同。传统戏曲表演是虚拟化的,因此可在面积不大的亭式舞台上演出,形成三面围观的格局。这类戏场以顶面敞开的庭院形式为其主流。本文讨论了下列相关声学问题:(1)亭式舞台的演唱效果;(2)庭院式戏场的混响感;(3)不同戏场布局的声场强度(响度)变化;(4)伴奏乐队位置变迁的声学效果;(5)舞台下设瓮助声之谜剖析。      

两扬声器虚拟声重放的双耳声压控制与定位性能

在两扬声器虚拟声重放中,通过精确重构双耳声压而产生不同的空间听觉感知。其重放的定位性能应该是由双耳声压控制的代价和稳定性所共同决定的。过去研究主要对双耳声压控制的稳定性进行分析,并以此作为扬声器布置和信号处理的依据。该文研究表明仅对双耳声压的稳定性分析是不足以完全衡量扬声器虚拟声重放的定位性能的。进一步采用虚拟声信号处理滤波器响应平均功率对双耳声压控制的代价进行分析。结果表明,缩窄左右对称扬声器布置的张角或采用非对称扬声器布置会明显增加产生侧向目标虚拟源时的双耳声压控制代价。虚拟源(虚拟声像)定位实验表明,双耳声压控制代价增加会引起虚拟源定位缺陷。实际应用中,为了有效产生侧向虚拟源,应避免采用过窄张角(如立体声偶极)和非对称的扬声器布置。     

Improve a 3D distance measurement accuracy in stereo vision systems using optimization methods’ approach

This paper presents a 3D distance measurement accuracy improvement for stereo vision systems using optimization methods A Stereo Vision system is developed and tested to identify common uncertainty sources. As the optimization methods are used to train a neural network, the resulting equation can be implemented in real time stereo vision systems. Computational experiments and a comparative analysis are conducted to identify a training function with a minimal error performance for such method. The offered method provides a general purpose modelling technique, attending diverse problems that affect stereo vision systems. Finally, the proposed method is applied in the developed stereo vision system and a statistical analysis is performed to validate the obtained improvements.     

Acoustics of Gonzago Theatre in the palace and Park Museum of Archangelskoje

The acoustic characteristics of a small theatre, situated in a wooden building built at the beginning of the XIX-th century, are investigated for the first time. The theatre is a part of the unique Russian architectural complex of Archangelskoje (the palace and park museum) near Moscow. Reverberation time, structure of sound reflections and energy criteria are measured. The analysis of the received results leads to the conclusion of a good sound quality.     

一种应用于大范围视觉测量的二维卷积光重心法

机器视觉由于具有非接触、可视化好、自动化和智能性高等优点,在航空航天、国防、工业现场等重要领域得到广泛的应用,其特征点的检测精度会大大影响视觉测量的精度。在研究视觉测量的光点中心提取技术的过程中,提出二维卷积光重心法,可有效地抑制光点边缘对光点中心位置的影响,大大地提高了光点中心的提取精度,既可以应用于发光特征点的提取,也可以应用于反光特征点的提取。利用该方法提取空间特征点进行三维重构的精度也比其他方法要高,能达到10^-4左右,基本满足工程测量的要求。     

Acoustics of courtyard theatres

The traditional Chinese theatre was often built with a courtyard. In such open-top space, the absence of a roof would mean little reverberation and non-diffused sound field. Acoustically the situation is quite different from that of any enclosed space. Therefore, the classic room acoustics, such as Sabine reverberation formula, would no longer be applicable due to the lack of sound reflections from the ceiling. As the parameter of reverberation time T30 shows the decay rate only, it would not properly characterize the prominent change in the fine structure of the echogram, particularly in case of a large reduction of reflections during the decay process. The sense of reverbrance in a courtyard space would differ noticeably from that of the equivalent 3D-T30 in an enclosed space. Based upon the characteristic analysis of the sound field in an open-top space, this paper presents a preliminary study on the acoustics of the courtyard theatres.     

Enhanced vision for adverse weather aircraft landing

Landing in poor weather is a crucial problem for the air transportation system of the future. To aid the pilots for these conditions several solutions have been suggested and/or implemented including instrument landing system(ILS) and microwave landing system(MLS) that put the responsibility of the landing to a large extent in the hands of the airport facilities. These systems even though useful are not available due to their high costs except in few major metropolitan airports. This shortcoming has generated interest in providing all weather capabilities not on the landing facility but on the vehicle itself. The Synthetic Vision System Technology Demonstration sponsored by the United States Federal Aviation Administration(FAA) and the US Air Force represents an effort to respond to the above needs[1,2]. In this paper we present a summary of a typical synthetic vision system. This system consists of a scanning 35GHz radar a scanning antenna, a signal/image processor and a head up display(HUD). The pilot is presented a final perspective image of the scene sensed by the radar with associated flight guidance symbology. This systems is implemented in real time hardware and has been under going tower and flight testing under a variety of weather conditions since early 1992.     

A review of the metal stud stiffness on the sound insulation of gypsum-board partitions

For the sound insulation of a double-panel partition,the stud between two leaves creates a vibration transmission path,which can often be more critical and more important in the mid-frequency range than the airborne path through the cavity.Owing to the fact that partitions with light-weight steel studs are commonly used in building construction,studies on the sound insulation effect of such studs have been conducted.Especially,a model,initiated by Gu and Wang(1983),has been widely studied during the past decades.In the model,the steel stud is considered as an elastic spring with its cross-section stiffness in the sound insulation index prediction of such a partition.Experimental results of different stud profiles have been reported from different testing laboratories and more information has been gained to understand the stiffness effect of the stud on the sound insulation of the double-leaf partitions.In this paper,the authors have given this subject a thorough review and have concluded that a critical problem needs further investigation on the determination of the stiffness of the connecting elements in the double-leaf partitions.     

Acoustic evolution of ancient Greek and Roman theatres

In this investigation the acoustic properties of ancient performance spaces for Greek and Roman drama were studied, from the viewpoint of material and design evolution. The paper first reviews the theatre evolution in antiquity. Following a systematic examination of computer simulation methodology for ancient Greek and Roman theatres, it then presents the results of a series of acoustic simulations in six typical theatre forms, using a beam-tracing program. Particular attention is paid to the scattering and diffraction from seat risers, which are important in outdoors theatres. Acoustic indices considered include sound pressure level, reverberation time and speech transmission index. The results show that in the evolution of ancient Greek and Roman theatres, changes in materials and theatre design generally resulted in acoustic improvements – the reverberation time had been increased and the sound level had been enhanced. Since the exact material characteristics are unknown, possible variations in acoustic performances are discussed based on simulations using a range of boundary absorption and scattering coefficients.     

Detection of extraneous abnormal sounds affecting road traffic noise by use of a necessary condition method

When measuring and/or recording road traffic sound levels during a long time interval, extraneous abnormal sounds will inevitably affect the road traffic sound levels of interest. Such sounds include those produced by horns, sirens, animals, construction sites, and the like. The detection and elimination of such extraneous sound requires much time and effort, but are necessary if noise indices such as L_eq, L_max, and L₁₀ are to be properly estimated. This paper proposes a practical detection method of these extraneous interfering sounds by deriving a necessary condition that road traffic sound levels must satisfy. The necessary condition provides an easy method of identifying sound levels not satisfying the condition, and distinguishes them as extraneous abnormal sounds, even in a large volume of observed data. The validity and usefulness of this method are confirmed by application to actually observed data.