Cortesia de Acoustical Surfaces

Keys To Improve Architectural Acoustics: Sound Absorption and Diffusion

由专筑网李韧，王雪纯编译

建筑“声学”的定义是改善环境中的声音，这是一门复杂的学科，但是我们可以通过了解一些基础的知识来进行高效的设计。首先，我们需要了解建筑声学中的两个技术类别，即隔音和声学处理。前者的意思是减少噪音，而后者的意思是让优化声音。

"Acoustics" in architecture means improving sound in environments. Although it is a complex science, understanding the basics - and making efficient and effective decisions - is much easier than you might think. The first step is to understand that there are two technical categories used in acoustics: soundproofing and acoustical treatment. Soundproofing means "less noise" and treatment, "better sound".


Cortesia de Acoustical Surfaces

隔音材料一般应用在录音工作室，同样也可以应用在靠近街道、学校、建筑区、交响乐区的附近。隔音材料就像是保护层，其结构一般都比较坚固，没有空隙。为了减少室内的噪音，可以将其应用在墙体、地板、天花板上，并且将门窗、开口设置地更加封闭一些。这些措施的效果也取决于噪音的程度，多少能够对室内产生帮助。

Soundproofing is commonly used in music recording studios - but it can also be applied in locations near major avenues, schools, construction zones or even drummers' neighbors. Soundproofing an environment is like protecting it against bad weather: the structure should be as solid as possible and without holes or cracks. To reduce the noise coming into and going out of a room, one must increase the structural mass of the walls, floor and ceiling, and seal the air gaps surrounding doors and windows, as well as the openings for refrigeration and electrical outlets. The extent of the measures taken will depend on how much noise there is on the outside, and how much you want it to be reduced on the inside.


（1）入射声音/（2）反射声音/（3）发射声音/（4）吸收声音


Cortesia de Acoustical Surfaces

另一方面，声学处理能够优化环境中的声音效果，就像人们想要听懂对方的言语，或者是学生们要理解老师的教学内容，以及观众们要欣赏高雅的音乐，诸如此类。各种建材都具有不同的声学特点，因为它们都能够吸收、反射、传播声音，当声音经过反射，就会在空间中产生混响或者回音效果，因此通过正确的声学处理就可以减少空间的混响与回音，其中人们一般所应用的方式有两种，即吸收与扩散，最好的策略便是同时结合这两种方式。

(1) Incident Sound / (2) Reflected Sound / (3) Transmitted Sound / (4) Absorbed Sound
On the other hand, sound treatments are used when you want to improve sound quality within an environment - for diners to hear and understand conversations at their tables in a restaurant, for students to understand teachers, for the whole audience to enjoy the music in an auditorium. All building materials have acoustic properties as they can potentially absorb, reflect or transmit sounds that reach them. When sounds are reflected, they cause an increase in the overall echo and reverberation levels in a space. When treating rooms correctly, echo and reverberation is reduced - and to treat rooms, there are two methods available: sound absorption and diffusion. The best treatment strategies combine these two techniques.


Cortesia de Acoustical Surfaces

吸收声音是指入射声音不再产生反射声音，比如打开的窗户就是一个吸收的容器，因为声音进入了就不会再反射回来。因此此种特效的目的是吸收声音，不让它反弹。总的来说，纤维材料的吸收性能比较好，而材料的密度越大，吸收性能则越弱。材料的吸收性能也与频率有关系，一般来说，频率低的声音波长较长，因此不容易吸收，但是人们对于低频的声音也不太敏感，所以并不需要针对此类声音做处理。

Sound absorption is defined as the incident sound that strikes a material that is not reflected back. An open window is an excellent absorber, since sounds that pass through the open window are not reflected back. Acoustic absorbers use materials designed for the purpose of absorbing sound that could otherwise be reflected back into the room. The more fibrous a material, the better the absorption, and denser materials are usually less absorbent. The acoustic absorption characteristics of different materials can vary significantly by frequency. In general, low frequency sounds are very difficult to absorb because of their long wavelengths. However, we are generally less sensitive to low frequency sounds, which means we often do not need to treat a room for low-frequency absorption.


表面的类别：（1）反射/（2）吸收/（3）扩散


Cortesia de Acoustical Surfaces


Cortesia de Acoustical Surfaces

声音的扩散是利用声音的传播来提升空间的声音质量，但是很多人不了解声音扩散的过程与工具。扩散的意思是反射声音在空间内传播，同时减少混响与回音。一种典型的扩散设施是弯曲的面板，这种面板一般会结合织物使用，放置在墙体或者天花板上。这样能够让声音扩散得均匀一些，否则，扩散声音会和原始声音结合起来，而降低声音质量。在音乐厅，声音的扩散能够提升声音的丰富程度，同时构成空间感。

Types of Surfaces: (1) Reflective / (2) Absorptive / (3) Diffusive
Diffusion is the method of spreading sound energy with a diffuser to improve sound in a space. However, the process and tools of sound diffusion can be misunderstood, even by some professionals. Diffusion spreads the reflected sound energy in a room, also reducing the harmful effects of strong echo and reverberation. One type of diffusor is a curved panel, often with a fabric cover, which can be easily placed on walls and ceilings. These types of panels have the advantage of uniformly spreading flat-wall reflections that would otherwise be combined with original sound waves to create destructive interference. In a concert hall, for example, diffusion panels are used to enhance the richness of sound and help create a sense of spaciousness.


Elinor Bunin Munroe Film Center / Rockwell Group. Image © Albert Vecerka / Esto

当室内应用吸收材料时，声波会对吸收材料的纤维与颗粒产生振动的效果，而振动因为摩擦而让热量降低，因此吸收声音的过程是热量转化的过程。针对大部分吸收材料而言，材料的密度和厚度都会影响吸收的声音量与频率，其原有的材质就决定了其吸收效果，但是人们也可以通过其他策略来提升声学性能。例如，吸声天花板和墙体后部的空气层就能够很好地提升低频声音的性能。

When a sound wave reaches an acoustic material, the sound wave vibrates the fibers or particles of the absorbent material. This vibration causes small amounts of heat due to friction and thus the sound absorption is performed by means of energy for heat conversion. For the majority of conventional acoustic materials, the density and thickness of the material affect the sound absorption amount and frequencies absorbed by the material. While the inherent composition of the acoustic material determines its performance, other factors may be used to improve or influence acoustic performance. For example, the incorporation of an air space behind an acoustic ceiling or a wall panel often improves low frequency performance.


Cortesia de Acoustical Surfaces

在房间里安装声音吸收器和扩散器，能够有效地降低劣质噪音，这是一个术语，例如安静环境中存在的干扰程度较低的噪音，以及大环境中较为嘈杂的声音。当噪音程度较高时，这些声音就会影响人们的正常交流。例如许多餐厅就缺乏吸收声音的措施，因此构成嘈杂的空间环境，人们在这里说话声音越大，能听到的声音其实越少。适当的声学处理能够减少声音的传播，让人们的交流更有质量。

By installing absorbers and diffusers in a space, the level of undesirable noise, in the form of echo and reverberation, is reduced. Noise is a relative term and can range from low levels of intrusive sound in a quiet environment to loud sounds in an already noisy environment. When noise levels are high enough, background noise can mask the speech sound levels that you want to hear. Restaurants can be classic examples of excessive noise interference due to lack of sound absorbing materials to prevent excessive build-up of echo and reverberation. Customers speak louder and louder to be heard and in doing so simply add to the noise. Proper acoustical treatments will helpreduce the accumulation of sound reflections and will reduce the need for customers to speak increasingly louder.


Cortesia de Acoustical Surfaces

在声学质量低下的空间里工作与生活的质量都不高，而且会直接影响到空间舒适度、人们的工作效率。但是建筑师并不需要过多地了解声学专业，可以通过让专业人员协助进行技术审查，同时选用适当的声学产品，就已经能够达到不错的声学效果。但是，基本的了解也有益处，这能够帮助建筑师进行正确的判断，将声音设计结合入项目之中，给使用者带来良好的体验。

Being in an environment with inadequate acoustics can be extremely unpleasant and directly influences the environmental comfort of a space, our behavior, and even our productivity. Just as architects do not necessarily need be experts in every technical aspect of a project, it is the same for acoustical knowledge – it can be helpful to call on acoustical-product suppliers to carefully review the technical specifications of a project and to recommend the best available products to improve the acoustical environment.However, it’s also helpful to have a basic idea of these issues – it will help us make informed decisions for incorporating better sound within the project's design, ultimately delivering a better user experience.


Cortesia de Acoustical Surfaces


Cortesia de Acoustical Surfaces