From the establishment of the Acoustic Laboratory of Tsinghua University in 1956, to the construction of the Great Hall of the People, to the National Grand Theater, to the perfection of the Bird's Nest Water Cube, to the large-scale construction of the iconic theater theater in China, let us review the development of architectural acoustics. course.
The Great Hall of the People laid the foundation for development
Figure 1 People's Hall of the People's Hall
Architectural acoustics development, from the 1959 Great Hall of the People in the Great Hall of the People, was the founding milestone. In order to welcome the 1959 National Day, Beijing built ten major buildings, and the sound quality of the Great Hall of the People was handed over to Mr. Ma Dazhao. Ma Dazhao organized research and design of acoustic experts in universities, architecture and broadcasting systems in Beijing, and created the first chapter of domestic architectural acoustics.
Firstly, the acoustic structure of the 10,000 hall is divided into six areas, each of which has different acoustic characteristics. The overall combination completes the overall acoustic effect, using mineral surfaces, plywood, etc. for acoustic structure calculation, experimental testing, and use. The sensational world's Ma Dazhao pioneered the micro-perforation sound-absorbing theory. The average sound pressure in the audience area of ​​the 10,000-meter auditorium must not be less than 70 decibels, and the sound pressure difference of any seat should not exceed ±3.0 decibels. For better conference speech clarity and reverberation time. Control is in 2 to 2.3 seconds.
Figure 20,000 10,000 Hall partition
According to Mr. Ma Dazhao's design concept, the Great Hall of the People first uses a decentralized sound source, not relying on several large speakers to amplify the sound, but the sound source on the podium is scattered to the seats under the table, each two seats are placed in front. A speaker, the speech on the listening platform is like the opposite. Considering that large-scale cultural events such as concerts are often held in the Great Hall of the People, the sounds of the performances must have a certain degree of fidelity, and the speakers in front of the seats are not effective, so a semi-distributed sound source is designed. The podium of the City Hall is 32 meters wide, and a channel is added in the middle of the left and right channels. The sound of one sound is gradually increased, the propagation time is controlled within 120 seconds, and the sound sounds continuous, sitting in the last row. The audience can hear clearly and will not be disturbed by echoes.
The sound quality design effect of the Great Hall of the People not only surpassed the Warsaw People's Palace, but nearly half a century later, it still can withstand the test of history: there is no larger town hall in the world, of course, it has not exceeded Its hall is sound quality.
When large-scale buildings in China began to focus on the design and application of acoustic environments, different acoustic structures and products emerged in different environments and requirements, ranging from simple plywood and mineral surface structures to wooden sound-absorbing panels, from soft sound-absorbing foams to soft sound-absorbing foams. Sound-absorbing materials and structures such as plant fibers have made great efforts in the improvement of the sound absorption of materials during this period. More in order to meet the different activities and broadcasting needs in sports venues, explore deeper expertise in theory and practice. It also laid the foundation for the development of acoustics, and gradually formed the necessity and professionalism of acoustics. With the advent of more functional buildings, the acoustics profession needs to go deeper, improving the standard of reverberation time and the index of sound field uniformity, which is followed by an increase in the form and technology of diffusion, and the profession begins to rise. In the era of the National Theatre, the architectural acoustic environment is not just a matter of professional technology.
Perfect acoustic application of the National Centre for the Performing Arts
Figure 3 National Grand Theatre
The acoustic environment in the National Centre for the Performing Arts is the focus of the building. Firstly, the appearance of the "eggshell" shape has the effect of rain noise, and the shape of the top is not easy to use the flat sound insulation, using sprayed fiber acoustic materials, Only the dome of Rw37 is increased to Rw47. The background noise in the Grand Theatre is about 25 decibels; the underground recording studio of the Grand Theatre needs the vibration sound insulation below the ground near the subway. The way to solve the vibration noise is to install a shock absorber for the recording studio, so the designer really let the house The "station" is on the spring damper. In the future, when musicians walk into the 200-square-meter studio on the ground floor of the National Centre for the Performing Arts, they may not be able to imagine that they are "hanging" on 400 springs. Professor Yan Xiang introduced that the Building Physics Laboratory of the School of Architecture of Tsinghua University undertook the experiment of spring vibration isolation of the studio. Under the studio of the Grand Theatre, which has been completed, the bearing capacity of each manganese steel spring is about 1 ton, and the design life is 100. year.
Different acoustic structures and materials are used in the various halls of the Grand Theatre, and MLS, GRG, and QRD diffusion structures are used on a large scale. In addition to adding an artistic atmosphere to the concert hall, the “Charm Top†in the concert hall is an acoustic consideration. Functional design. For the concert hall, the first important thing is the sound. All architecture and decoration design must serve the sound. The uneven ceiling is more conducive to the spread of sound. The embossed ceiling of the irregular pattern is a sound diffuser that spreads the sound from the stage to every corner of the auditorium.
The embossed ceiling is just one of the big theater acoustics "the door", the architectural design of the acoustics is everywhere. The interior of the opera house looks elliptical, but the shape seen by the audience glasses is a "fake phase." Professor Yan Xiang, from the Architectural Physics Laboratory of the School of Architecture of Tsinghua University, who is responsible for the indoor sound quality test of the Grand Theatre, said that from the visual point of view, the elliptical theater on the curved wall will be more beautiful, but the arc is fatal to the sound quality. of. The rectangular shape is good for reflecting sound, and the sound quality is the best, but it looks old-fashioned. Finally, the designer used a best of both worlds.
Now, the wall of the rectangular opera house is covered with metal mesh, so that the wall of the opera house looks like a circular arc, but the sound can be projected through the metal mesh to the real wall behind the metal mesh. The on-site staff told the reporter that a decorative light was installed between the metal mesh and the wall. The light reflected the red wall behind the metal mesh, and then through the golden mesh surface, it looked magnificent. Welcome to China Home Theater Network!
"There are also many inside shows." Professor Yan Xiang said. Although the debate on the Grand Theatre is endless, several engineers who participated in the work of the Grand Theatre expressed similar views: many innovations in technology and design concepts in the Grand Theatre will bring inspiration to future buildings in the country. Welcome to China Home Theater Decoration Network!
The success of the National Centre for the Performing Arts allows people to feel the audio-visual enjoyment brought by architectural acoustics. They can listen to the beautiful music beside the strong vibration of the subway. They can hear the sound of the venue after the sound-proof observation window, and these are rigorous theoretical arguments and Hundreds of trials of professional technology and products began to be applied in more engineering. The shock absorption and sound insulation of various computer rooms uses mechanical vibration induced by air cushion and spring-type elastic shock absorption, while mechanically Sound source soft processing. The application of low-frequency sound-insulating glass in the simultaneous interpretation room of the National Convention Center is also a breakthrough in the field of glass sound insulation. The low-frequency sound-insulating glass is a specific proportion of solid structure and transparent damping, which reduces the low-frequency resonance characteristics, and the sound insulation after sealing is as high as possible. Rw53 decibels, equivalent to the sound insulation of 24 brick walls.
With the completion of the exemplary acoustic architecture and the great development of the domestic cultural industry, the development and construction of theaters and theaters in various places have been promoted, and the acoustic environment has been built with the theory of architectural acoustics. Based on this, various performances have been completed, not only that. Acoustic environmental indicators such as lecture halls and clubs have also been qualitatively improved and applied, and people are more exposed to the experience and feelings brought by a good acoustic environment. Architectural acoustics are valued and applied in various environments.
Acoustics case of stadiums and theaters (picture from Coke Acoustics Design Center) Acoustics is simple to use in home theater
Since 1976, Dolby Laboratories has invented the Dolby Stereo Cinema System, which denoises the four channels of the left, center, right, and surround channels and records them into two channels in a certain way. In playback, the opposite way is restored to four channels (ie 4-2-4 mode), thus achieving multi-channel and two-channel compatible transmission. In the "Star Wars" filmed in the late 1970s, the Dolby Surround System successfully achieved the synchronization of the sound direction and the movement of the picture, allowing the audience to feel the sense of position and the sense of presence of the sound from the top of the head, causing the film industry. After the vibration, the audio and video equipment and the reduction performance and sound field form are constantly improved and enriched, can this kind of impact be taken home! In 1982, Dolby began to cooperate with Chinese cinemas. In 1998, it established a representative office in Shanghai and began to provide authorization for the use of Dolby technology in China. At present, almost every Chinese company that produces audio and video products uses Dolby technology. The trademark "Dolby" is almost marked on every audio and video product in China. However, such equipment reduction performance has not completely brought the impact home, mainly from the lag of architectural acoustics, and with the increasing demand for audiovisual, many engineering materials and structures have begun to be used by home residents.
Enthusiasts began to think about using architectural acoustics to adjust the sound field of the room. In the early days, the sound-absorbing materials were mainly used to reduce the reverberation time in the room, and the effects of restoration and rendering of the equipment, such as mineral wool, were more clearly heard. The matching of perforated plywood, or the use of wooden sound-absorbing panels, although the effect is improved, but the amount of sound absorption brings the fullness and dryness of the sound, the generation and processing of standing waves, how to use diffusion, etc. Troubled, people gradually discovered the importance of professional acoustic design;
Therefore, it is proposed to make acoustic treatment requirements similar to professional cinemas in the home theater. The equipment manufacturer Linyi Theater's decoration style is used for the acoustic design of the home theater environment, using wooden sound-absorbing panels, mineral wool and soft bags to fill in the home theater. The diffused structure in the simulated theater is placed directly into the room. However, the structure, fit and material of the sound absorbing material will produce different sound absorbing coefficients. The overall fit has a great influence on the reverberation time. In the end, the result of the poor experience is experienced by the operators and users in the acoustics profession. Short board.
Private cinema sound field adjustments generation and application
Many acoustic designers and professional companies have introduced sound field adjustments or tuning bodies for use in home theaters for home theaters, with separate sound-absorbing blocks, geometric diffusion, MLS diffusion and QRD diffusion as the single item for sound and sound room sound field adjustment. If the average sound absorption coefficient of the room is insufficient, a separate sound absorbing block can be used, and the sound absorbing block can be diffused in a "checkerboard", "strip form", or "patched" distribution, and the sound diffusing plate is used to combine the geometric diffusion and spread separately. The MLS and QRD are used for one-dimensional or two-dimensional diffusion, and the MLS diffusion can be combined into a sound absorbing body. The defects such as echo can be adjusted, but the standing wave at the female corner is formed because it is a simple monomer to adjust. The completion of the standing wave reduction on the whole, resulting in the adjustment and use of the single low-frequency trap products, these have brought preparation and inspiration for the development of the overall development of home theater technology.
In the home environment, professional, environmental protection and aesthetics require higher requirements. Simple sound adjustment forms do not better complete professional sound effects and aesthetics. Environmental protection needs further improvement. The overall design of private cinema acoustics requires higher standards and requirements. .
The high standards of private cinema are popularized and applied in China.
As home theater technology trains a large number of THX acoustic engineers in the country, THX standards are widely adopted. Room Acoustics Design As the most critical part of home theater design, THX has developed 8 evaluation indicators for private cinema: 1. Dialog clarity and articuiation dialogue clarity and standardization; 2. Precise soundlocalization accurate sound localization; 3. Smooth sound movenent Smooth sound image movement; 4, Spacious suitound surround sound field; 5, Smooth tonal balance balanced sound; 6, Tight bass fast and compact low frequency performance; 7, Fuli dynamics wide dynamic range; 8, Every seat a good seat is the emperor position; and in this standard how the acoustic environment of the private theater is designed, setting a high threshold for simple acoustic adjustment, the acoustic design of the private theater requires a more professional overall design and Calculation, starting from the selection of the room in the private theater, not only choose the appropriate proportion of the room shape, large space, etc., but also to check the room's waterproof, fresh air, and the overall background noise of the audio-visual room should be less than 30 decibels, eliminating the sound Indoor and outdoor interference to ensure that background noise affects early decay of subjective feelings EDT, to ensure the perfect feeling and data of the reverberation time, the room starts from the sound insulation design, the sound of the impact generated from the wall, the ceiling and the ground, the sound of the air generated by the doors and windows and the low-frequency vibration of the long amplitude, low frequency Low valley resonance and direct low frequency penetration, avoiding the resonance of the tuyere, keel and mounting material during construction. In reverberation, echo and standing wave, the overall design is required. The wall obliquely is more suitable for the designer's geometric diffusion. Reflecting the sense of design and overall aesthetics, without the influence of background noise and resonance, the reverberation time can complete the data requirements more accurately according to the combination of suction and expansion, and bring more perfect subjective feelings. The processing of echo and standing wave also changes. It has to be "sleek" and diverse, and the treatment style can also change the use and processing of "low frequency traps", and add the original adjustment items to the overall aesthetic design, thus completing the private requirements of higher requirements and standards. In the cinema acoustic environment, the home theater's environmental decoration has transformed into a standardized overall acoustic solution. China Home Theater Decoration Network
The construction period, energy, quality and other factors of the decoration and decoration are mainly the user's requirements for aesthetics, environmental protection and quality to set a goal for the development of the acoustic environment of the home theater. On-site construction can not guarantee the construction quality and material processing quality, paint surface, chemical glue Inevitable use also causes on-site construction to bring defects that cannot be zero-contaminated. Various requirements and objectives require separate certifications and standards for the home theater acoustic environment.
Custom sound field requirements standards and completion
From traditional home theater acoustic design and construction, to standardized design and products, relying on a large number of practical cases and summing up many years of design experience, the CLP Acoustic Design Center's private cinema standardized indoor acoustics overall solution proposes a higher professional standard: 1, better room proportion and room position; 2, strict background noise environment (background noise is less than 30dB); 3, eliminate the influence of resonance (resonance sound is less than 15 dB); 4, satisfactory clarity, fullness of the mix Ringing time (between 0.2-0.4s); 5, sufficient loudness and uniform sound field (sound field uniformity is less than 3 dB); 6, professional basis, more beautiful, efficient, environmentally friendly high quality requirements.
The actual description of the standard completion according to a case in Beijing:
I. Project Overview:
A large-scale real estate in Beijing is always an audiophile. There is a set of housing on the 7th floor of the high-end residential building that I have developed. I want to make the second bedroom into a top-class theater. (See Figure 1) The specific structure of the room is 5.6 wide and 4.95 meters high. M, requires both film and HI-FI functions, while ensuring the sound insulation design and environmental standards.
Figure 1 room sound design plan
Second, site survey:
After the site survey of the acoustic engineers and related technical personnel of the design center, the following questions were raised: 1. The strong and weak electricity of the theater, the new wind, etc. need to be grounded before the sound insulation starts. 2, the air conditioner needs to install the muffling pipe and arrange it in advance, 3, Because the living room is directly facing upstairs and downstairs, the left and right sides are the master bedroom and the study room. It is very difficult to handle the sound insulation. It is necessary to design the room in the room and consider the load of the structure. 4, sound insulation and sound absorption treatment After that, it will reduce the volume of the room. 5, the space is small, the cabinet body is embedded in the side wall of the audio-visual outdoor, and the sound insulation design is made outside the cabinet.
According to the site survey, the data is collected into the statistics of the data collection table, which also includes: the original structure size, the original structure shape, and the form of each connection point, as well as the device model, performance, size and required style;
Third, the room acoustics design indicators:
According to the different functional requirements of small space, the acoustic indicators are not the same. For this project, the design center proposed that the indoor background noise meets the NR-30 curve requirement, the reverberation time is required to be 0.4±0.2S, and the room and sensitive room sound insulation is greater than or equal to RW65dB, eliminating the acoustics such as standing wave, resonance, tremor echo, and acoustic dyeing. Defects, and carried out simulation data analysis to analyze the structure of sound defects generated in the field;
Fourth, sound insulation design
1. There is a problem of poor sound insulation in ordinary residential floors.
In the current residential design, the practice of the floor is mostly the concrete floor with a plastering finish. Due to the rigidity of the concrete slab and the poor damping effect, the sound insulation of the impact sound is very poor. Percussion sound insulation refers to the insulation performance of the floor from the upstairs footsteps, the children's running sound, the sliding sound of the furniture, etc. According to the current "Code for Design of Sound insulation for civil buildings" GBJ118-1988 and "Code for Residential Buildings" GB50368-2005 (full text strong bar) "7.1 noise and sound insulation", residential floor slamming sound insulation index Lpn, w should be less than or equal to 75dB, and the concrete floor slab Lpn, w are more than 80dB. Therefore, most of the design houses are residential buildings designed according to concrete slabs, and the sound insulation of the floor slab can not meet the use of the theater. Improve the sound insulation of the room in the design of the house
2.1, floating ground sound insulation design
The most effective method for sound insulation on the ground is the “floating ground†method, that is, laying a layer of damping layer on the structural floor (usually 4-10mm thick), and then pouring concrete on it (generally 40-80mm, need to be reinforced), Form a "sandwich" elastic sandwich structure. According to the conclusion of the building physics laboratory of Tsinghua University, the sound insulation of the vibration-damped floor-mounted floating floor can be improved by 18-22dB (related to the material and elasticity of the floor mat) than the original concrete floor. The sound volume Lpn,w can be reduced from 80dB to 56-58dB, greatly reducing the living noise upstairs. This construction practice has become increasingly mature. The “floating ground†structure has been adopted in real estate projects such as Beijing Olympic Garden, Shenzhen Hongshu West Bank, and Zhejiang Jinhua Tianlong Land. The measured data fully meets the national standards, and the sound insulation effect is very satisfactory.
In addition, the construction of the damping wood floor on the concrete floor has greatly improved the sound insulation of the floor. Including solid wood flooring (with keel) and composite flooring have good impact sound insulation effect, Lpn, w measured value is generally less than 70dB, to meet the requirements of residential design specifications. According to the investigation of the Building Physics Laboratory of Tsinghua University, it was found that there were few complaints about the sound insulation of the floor slabs using the wooden floor in the hardcover houses, indicating that the wooden floor can play a good sound insulation effect on the floor. Welcome to China Home Theater Network!
It should be noted that although the floating ground mechanism improves the sound insulation of the ground, the sound in the theater will be transmitted to the upper and lower floors through the vibration of the top surface and the wall surface, so the sound insulation ceiling and the sound insulation wall are to be made. Face, that is, the structure of the room.
Figure 2 floating floor structure diagram
2.2, elastic sound insulation ceiling design
We use elastic ceiling, double structure laying soundproof felt 9mmFC board, 100mm elastic hanger with wooden side fixed grid, 50mm environmental sound-absorbing cotton filling, full 12cm FC board 9FC board, clip 6 PCT imported damping felt. In order to increase the sound insulation, we designed a two-layer composite structure with an air layer in the middle to maximize the sound insulation design at a limited height.
Figure 3 elastic sound insulation ceiling
2.3, sound insulation design of composite structure wall
In order to ensure a high sound insulation of 65dB, the wall surface is an extremely important part, and there are doors and windows that are easy to leak sound. The sound insulation of the door depends on the sound insulation of the door itself and the degree of sealing of the door seam. The sound insulation of ordinary wooden doors is only 12-15dB. If the door is made into a multi-layer composite sandwich door, 50mm rock wool is used as the door leaf in the middle, so that the door can increase the sound insulation by 5-7dB. Professional soundproof door, the highest sound insulation of steel can reach more than 45dB, but it must be handled in the door frame. If the wooden professional soundproof door is made on site, double-mouthed with felt seal or sealed with EPDM rubber, we Through the experimental test, the sound insulation amount of 39-41dB can be achieved. Due to the high noise requirements of the project owner, we have made a 50cm sound lock to improve the sound insulation of the entrance door. The first wall of the sound lock is made of red brick 20cm brick wall (for most of the The slab must take into account the load of the slab when making red bricks, because this case is on the reinforced beam of the structure, which can reach 650 kg per square meter by calculating the load, plus a cavity of 50 cm to make a composite structural wall. Body, thus ensuring the overall sound insulation of the room. See Figure 4 for details.
Figure 4 wall sound insulation design
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