学术英语论文WHAT MAKES A GOOD LISTENING ENVIRONMENT.doc

what makes a good listening environment englishwhat makes a good listening environment-study of some acoustic principles in our rehearsal buildingli-genshi xing-yananabstract rehearsal building is an important place for our daily live. there are 216 rooms in our rehearsal building and at lest one piano in each. what ensures that they wont disturb each other when students play the piano at the same time? what makes a good listening environment in such a narrow space? compared with normal buildings, there are some acoustic principles in the designing of the rehearsal building.key words acoustic, reverberation time, sound absorption and sound insulationpart 1: architectural acousticswhat we discuss here belongs to the area of architectural acoustics. what is called the architectural acoustics? it includes the born, propagation, utilization and controls of sound waves which all relate to the buildings. it is a dual discipline, part of acoustics. in the broad sense, structural acoustics includes environmental acoustics and noise control. noise and tone quality must be considered in the design process of rehearsal building, concert, recording studio and recital hall. generally speaking, the designing of auditorium is more concerned in architectural acoustics.part 2: key pointsthere are several key points in the designing process: reverberation time, sound absorption material and sound insulation.reverberation timereverberation time is a vital acoustical characteristic of a loom. defined as the time necessary for a sound to decay to one millionth (.000001) of its original intensity.in a rehearsal room, suitable reverberation time can make sound harmonic. too long time make music lack of rhythm and dynamics. the larger the room, the larger the reverberation time; the smaller the room, the shorter the reverberation time is. just what the ideal time is varies with the musical medium and style; reverberation times shorter than about 1 .0 sec or longer than about 1.7 sec are rarely satisfactory.t experiment 1：same birdcall, different reverberation timeyou will be given a sound of birdcall. from the different reverberation time you can hear the change of the birdcall. sabin, the founder of architectural acoustics, gave his reverberant expression as early as 19cen. t=0.049 * v/ ast: reverberation time; v: room volume; s: wall acreage; a: sound absorption coefficient of the wall. the term a is calculated as the sum of the surface area (in m²) times the absorption coefficient (a) of each material used within the enclosure, as follows: as=a1s1+a2s2+a3s3+.t experiment 2：account the reverberation time of our rehearsal buildingobject: room 324(in our rehearsal building)measure tools: tape measure(30m)measure result：materialconcrete wall（floor board）wooden floorglazingcarpetcottonceilingresult：v=26.45(m3) as=5.379(sabin)t=0.792(s)conclusion：the reverberation time in room 324 is approximate to1second(error being)，according with the optimum reverberation times.optimum reverberation timessuch a formulation is particularly useful as it starts to recommend the most effective volume of rooms for particular reverberation times. given that we know the range of values of rt for specific purposes, we can determine a relationship between room volume and internal surface area. from this ratio, and the fact that each member of the audience increases the amount of absorption in the auditorium, volumes of rooms can be specified in m³ per person, which is a very useful figure at the initial stage of design. sound absorptionhow sound is absorbed?sound energy is absorbed when it is converted to another form of energy. in most cases, this takes the form of conversion to heat. this results from the actions of friction and the resistance of various materials to movement and deformation. on the surface of the sound absorber, there are many little holes. when a sound comes to the surface, go into the little hole, reflection will be happened until sound energy changes into heat energy. this process is called diffraction. porous absorbers such as mineral wool, fiberboard or plastic foams have an open pore structure. conversion to heat is produced by friction when vibrating air molecules are forced through the pores and interact with the pore walls. these are effective primarily for high frequencies with short wavelengths. diffraction will be occurred when the hole size is shorter than the wavelength. . the sound frequency we can hear is from 20 to 20000hz,(wavelength is between17mm to 17m). so in our rehearsal rooms, porous absorbers hole size is all smaller than 17mm.every material has its own absorption coefficient.from this table, we see that carpet is good for the sound of high frequency. but bourdon is more troubled. rehearsal room uses the resonance to deal with unwanted bourdon. sound insulationthe sound transmit in two main ways, one is in air, the on the is though the structure. so if we want a good insulation effect, these tow ways must be treated carefully.first, by weight. the wall and floor can transmit the sound energy by resonance. it depends on the weight of wall, floor. thick concrete wall is better to avoid structure resonance. also the door should be thick and heavy enough.second, by air. no matter what ways we choose to insulate sound, air proof is most important. if the opening of room is larger than 10% of whole surface, all efforts seem useless. a small hatch will destroy all efforts. strips of rubber are used to stop air fromg transmitting sound out.the position of wall and window plays an important roll in sound insulation. when window is open, part of sound diffract. traditional design can not solve the diffracted sound. rehearsal buildings design makes all the windows not state out in straight line, but cater-corner. it makes one rooms window facing an other rooms side wall. sound will never go into other rooms through windows. in corridor, one rooms door faces the wall of room opposite. there is no instance that two door are face to face. this design reduces noise that comes from other room to minimum.part 3：our research is based on the predecessors theory. limited to knowledge and measure tools, our result exists some error. but study has a long way to go. wish more people who are interested in this subject join us. lets do it better! thank you!reference materialdonald. a .hodges刘沛. 音乐心理学手册（第2版）.m.湖南：湖南文艺出版社，2006andrew marsh. the university of western australia online information and course notes. 中文什么营造1个好的听觉环境琴房的声学环境研究中国音乐学院艺术管理系03级学生 邢亚楠 李根实摘要琴房是同学们日常学习练琴的重要场所，研究琴房的声学环境对音乐学院的学生来讲是至关重要的。我们的学生琴房共216间，每间至少1架钢琴。在1个狭小的房间内，如果这么多人同时练琴，如何保证互不干扰，从而创造1个良好的听觉效果，是我们要研究的1个课题。本文将从建筑声学、混响时间、吸声、隔声4个方面进行研究。 关键词声学，混响时间，吸声，隔声1、 建筑声学我们所研究的课题属于建筑声学范畴。建筑声学是研究与建筑相关声波的产生、传播、利用及控制的学科。它是声学的1个分支，是1门边缘学科。广义来说，建筑声学包括环境声学和噪声控制。由于人们关心观演建筑声学，所以建筑声学多指观演类建筑即厅堂声学设计。琴房，排练厅、音乐厅，录音棚的设计建造过程要考虑噪音，音质等问题。2、 常用重点考虑的几个因素混响时间、吸声、隔声1、混响时间在厅堂（室内）声学设计中，混响时间是1个重要的概念与指标。声音在室内衰减的过程称之为混响过程。声音在室内将从稳态开始衰减，直至衰减到其声能为原有声能的百万分之1时，这段时间被称为“混响时间”，也即衰减60db所需的时间，记作（rt或t60）。在厅堂内，适度的混响时间，可使音乐丰满，语言宏亮、饱满。过短的混响时间使声音干涩无力；混响过长将使语言清晰度降低，音乐缺乏节奏感和力度，唱词模糊不清。混响时间受制于两种室内的性质：音量和吸收。室内空间越大，混响时间就越长；室内空间越小，混响时间越短。当房间容积越大，界面吸声量直小时，则每次反射经过的路程就越长，声音衰变就越慢，因此混响时间将越大。理想的混响时间也不是固定不变的，它有赖于音乐的媒介和风格。1般说，短于1.0秒或长于1.7秒的混响时间，是难以令人满意的。实验1：制作1个声源（鸟叫声，长达3秒），通过给声源加上不同的混响时间（时间间隔为1秒），来听不同混响时间状态下声音的不同。 研究建筑声学的开山老祖师，sabin 早在109世纪末就提出他以简单的马表所测出的混响公式: t=0.161 * v/ as其中t就是残响时间，v是房间的体积，以立方米为单位，s是墙壁的面积，以平方米为单位，a是墙壁的吸音系数，以sabin为单位。如果墙壁使用的材料不只1种，那总沙宾值可以由 as=a1s1+a2s2+a3s3+. 实验2：实地测量通过计算：v=26.45(立方米) as=5.379(sabin)代入公式:：t=0.792(s)实验结果：琴房324的混响时间趋近于1秒（存在误差），基本符合适宜的混响时间。2、吸音原理：吸音材料表面有许多小孔，声音从声源发出，传播到吸音材料表面，进入小孔后，便会在结构有点像海绵的内壁中胡乱反射，直至大部份声波的能量都消耗了，变成热能，达到了吸音的效果。（图）为什么声音进入小孔以后就改变传播方向胡乱反射了呢？这是因为声波的衍射。声音在通过尺寸比自身波长小的孔洞的时候，就会发生衍射，孔洞成为1个新的声源。人能听到的声音频率大概在2020000hz左右，其波长为17mm17m，所以吸音孔的尺寸都在17毫米以下。每1种材料都有1定的吸音系数从以上表中可以看出，用毯子来吸音，对高频声音的效果很好，但是低音就差1些，琴房使用了共振原理来吸收多余的低音。镶在墙裙上的特定体积的盒子可以对相应定范围的低频声音产生共振，盒子里面填充的玻璃纤维或替代物可以把盒子振动的能量吸收，从而达到吸收多余的低频声音。3、隔音因为声音传播的途径主要有两个方面：第1，空气传播；第2，建筑物结构传声