The record of architectural acoustics was first seen in the first tenth century BC, written by the Roman architect Vitruvius. The book describes the sound adjustment methods in the ancient Greek theater, such as using the resonance cylinder and the reflecting surface to increase the volume of the performance. In the Middle Ages, European churches used large interior spaces and walls with low sound absorption to create a long reverberant sound, creating a mysterious religious atmosphere. At that time, a resonator that absorbed low-frequency sound was also used to improve the sound effect of the theater.
In the 15th and 17th centuries, some of the theaters built in Europe mostly had ring-shaped boxes and stepped seats arranged close to the ceiling. At the same time, due to the absorption of sound energy by the audience and clothing, and the scattering of sound by the complicated concave and convex decoration inside the building, The reverberation time is moderate and the sound field distribution is relatively uniform. This design of a theater or other building may have only sought to solve the problem of sight, but inadvertently achieved a good hearing.
In the 16th century, China built the famous Beijing Tiantan Huangyuyu, which has a 65-meter-diameter whispering wall, which can make a weak sound spread a hundred or two meters along the wall. In front of the steps of Huang Yuyu, there are three sound stones that can hear several echoes.
In the 18th and 19th centuries, the development of natural sciences promoted the development of theoretical acoustics. By the end of the 19th century, classical theoretical acoustics had reached its peak. At the beginning of the 20th century, American Sabin proposed the famous reverberation theory, which made architectural acoustics into the field of interest. Since the 1920s, the introduction of tubes and the application of amplifiers have enabled the measurement of very small acoustic quantities, which has opened the way for the further development of modern architectural acoustics.
The basic task of architectural acoustics is to study the physical conditions and acoustic processing methods of indoor acoustic wave transmission to ensure that the indoors have good hearing conditions; to study and control the noise interference and damage in a certain space inside and outside the building.
The methods of indoor acoustics include geometric acoustic methods, statistical acoustic methods, and wave acoustic methods.
When the indoor geometry is much larger than the wavelength of the acoustic wave, the geometrical acoustic method can be used to study the early reflected sound distribution to enhance the direct sound, improve the uniformity of the sound field, and avoid the sound quality defects. The statistical acoustic method is to study the excitation of the continuous sound source from the energy point of view. The process of increasing, stabilizing and attenuating the density of sound energy (ie, the reverberation process), and giving the exact definition of the reverberation time, combining subjective evaluation criteria with acoustic objective quantities to provide a scientific basis for indoor acoustic design; When the size is comparable with the wavelength of the acoustic wave, the resonance phenomenon is easy to occur. The wave acoustic method can be used to study the normal vibration mode and the generation condition of the indoor sound to improve the uniformity and spectral characteristics of the sound field in a small space.
The interior acoustic design includes the choice of body shape and volume, the selection and determination of the optimal reverberation time and its frequency characteristics, the combination of sound absorbing materials and the design of appropriate reflective surfaces to reasonably organize the near-resonant sound.
Acoustic design should take into account two aspects. On the one hand, it should strengthen the effective acoustic reflection in the sound transmission path, so that the sound energy can be evenly distributed and spread in the building space. For example, in the sound quality design of the hall, it should be ensured that the audience seats are appropriate. Loudness. On the other hand, various sound absorbing materials and sound absorbing structures are used to control the reverberation time and the specified frequency characteristics to prevent echo and sound energy concentration. Acoustic model tests are performed during the design phase to predict the effects of the acoustic measures taken.
On the one hand, it is necessary to understand the influence of the indoor space and the selected materials on the sound field. Also consider the relationship between the acoustic parameters of the indoor sound field and the subjective hearing effect, that is, the subjective evaluation of the sound quality. It can be said that the quality of the indoor sound quality is determined, and ultimately it is the subjective feeling of the audience. Due to the individual perception and discretion of the audience, the inconsistency in subjective evaluation is one of the characteristics of the subject; therefore, architectural acoustic measurements are used as research. Exploring the correlation between acoustic parameters and the subjective perception of the audience, as well as the relationship between the subjective perception of indoor acoustic signals and the indoor sound quality standards, is also an important content of indoor acoustics.
In large hall buildings, electro-acoustic equipment is often used to enhance natural sound and improve the uniformity of direct sound. Artificial delay and artificial reverberation can be used in the circuit to improve the sound quality. Indoor sound reinforcement is an indispensable aspect of sound quality design for large halls. Therefore, modern sound reinforcement technology has become an integral part of indoor acoustics.
Even if there is a good indoor sound quality design, it will be difficult to obtain good indoor hearing conditions if it is seriously disturbed by noise. In order to ensure the use of the building and to ensure normal living and working conditions, the impact of noise must also be reduced. Therefore, controlling the noise of the building environment and ensuring a certain standard of quietness inside the building is another important aspect of architectural acoustics.
Noise interference, in addition to the noise intensity, is also related to the spectrum duration of the noise, the number of repetitions, and the human auditory characteristics, psychology, and physiological factors. Controlling noise is to control the noise within an appropriate range according to actual needs and possibilities. The highest noise standard allowed is called the allowable noise level, that is, the noise tolerance standard. For buildings with different uses, there are different building noise tolerance standards: for industrial buildings, mainly for the protection of human health, and for the study and living environment to ensure a certain standard of quiet.
In noise control, the acoustic radiation intensity of the noise source is first reduced, followed by the control of noise propagation, and personal protection measures are again taken. Noise can be divided into two types according to the propagation path: one is the noise transmitted by the air, that is, the air sound; the other is the noise radiated by the mechanical vibration transmitted by the building structure, that is, the solid sound. The attenuation of the airborne sound is greatly reduced by the attenuation of the propagation process and the partition wall; the solid sound is very small due to the attenuation of the acoustic energy of the building material, and can be propagated far away. Usually, the separation member or the elastic joint is used to weaken the propagation.
The ability of a building to sound sound insulation depends on the amount of sound in the wall or partition (interrupted). The basic law is the law of mass, that is, the amount of sound insulation of a wall or partition is proportional to the logarithm of its areal density. Due to the extensive use of lightweight materials and lightweight structures, modern buildings have reduced the ability to provide sound insulation for air. Therefore, double-wall structures and multi-layer composite wall panels have been developed to meet the requirements of sound insulation.
It is relatively difficult to achieve solid sound insulation in buildings. The general vibration isolation method, such as the use of discontinuous structures, is complicated to construct, especially for modern buildings that require a high degree of integrity. When people walk around the floor or move objects, they produce impact sounds, which directly cause noise interference to the building's room. The standard strik can be used to strike the floor and the sound pressure level is measured downstairs. The greater the sound pressure level value, the worse the performance of the floor slamming impact sound.
The main method for controlling the impact sound of the floor is to provide an elastic layer on the floor surface layer or between the floor panel and the load-bearing floor board, especially the elastic surface layer on the floor board, which is a simple and effective measure for isolating the impact sound. In industrial buildings, soundproof rooms or sound enclosures have become widely used means of reducing equipment noise.
The vibration isolators are arranged under the mechanical equipment to reduce vibration, which is the main measure for vibration isolation of construction equipment. At present, the vibration isolator has been developed from a design to a stereotyped product.
Since indoor acoustics is closely related to the volume, shape and interior surface treatment of the building space, the room acoustic design must be determined from the architectural point of view. Achieving good acoustic function and a highly uniform effect of architectural art is the common goal of collaboration between scientists and architects.
To improve the acoustic environment of buildings, basic research, technical measures and organizational management measures must be strengthened. Although the focus should be on sound sources, it is often difficult or even impossible to change the sound sources. Therefore, more attention should be paid to the transmission routes and receiving conditions. . Various control technologies involve economic issues, so comprehensive research must be carried out in cooperation with relevant various professions to obtain the best technical and economic benefits.
Other acoustic branches
Sub-acoustics, ultrasound, electroacoustics, atmospheric acoustics, musical acoustics, speech acoustics, architectural acoustics, physiological acoustics, bioacoustics, hydroacoustics
Other branches of physics
Physics Overview, Mechanics, Thermal, Optics, Acoustics, Electromagnetics, Nuclear Physics, Solid State Physics
Other branches of architecture
Architecture Overview, Building Physics, Architectural Optics, Building Thermal Engineering, Architectural Acoustics, Architectural Economics, Building Structures, Architectural Design, Interior Acoustics, Interior Design, Landscape Architecture, Urban Planning, Civil Engineering, Engineering Mechanics, Water Mechanics, soil mechanics, rock mechanics, coastal hydrology, road engineering, traffic engineering, bridge engineering, hydraulic engineering
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