The Ministry of Construction issued two documents, JGJ/T131-2000 “Design and Measurement of Acoustics for Gymnasiums†and JGJ/3J-2003 “Design Specification for Sports Architectureâ€, among which the indicators and requirements for acoustic design include the following:
(1) The acoustic conditions of the gymnasium should be based on ensuring that the language is clear;
(2) Do not produce obvious sound defects such as sound focusing, echo, and tremor echo;
(3) The reverberation time of small and medium-sized stadiums should be set in the range of 500~1000Hz: 1.3-1.5s;
(4) Sound-absorbing materials or sound-absorbing structures shall be provided above the hall;
(5) The glass windows around the hall should be provided with absorbing curtains;
(6) The large wall surface should be absorbed and treated;
(7) The low walls around the playing field and the stands should be equipped with sound-absorbing structures, or control the tilt angle and shape.
Common acoustic defects in stadiums
In recent years, architectural forms and structures of gymnasiums have used exposed grids, ceilings, and even light-transmitting roofing materials. Popular arched domes, circular walls, and large-area glass windows or glass curtain walls have all become easy. Causes more serious acoustic defects. Moreover, architectural acoustics design projects are often only involved in the later stage of civil construction design, decoration design and construction. Since the basic architectural modeling has been difficult to change, the only way is to adjust and reform the acoustic decoration structure. This greatly increases the difficulty of design and construction.
Common acoustic deficiencies are as follows:
1, sound focus
The sound will produce sound focus when it meets a concave wall or ceiling, making the sound pressure level of some points or areas much larger than other positions, resulting in very uneven sound field distribution, "sound staining" and "sound Feedback whistle" and other sound quality defects. The arched vaults and circular walls of the stadium are typical structures that are easily focused.
2, tremor echo
Between a pair of parallel walls in the room, a sound is reflected back and forth between the two walls to produce multiple repetitive sounds that become vibrating echoes. This is most likely to occur in the large wall areas of the stadium, as well as in the low walls and stands around the venue.
3, long reverberation time
Compared with the general theater, concert hall, conference hall and other halls, the gymnasium can do sound absorption processing with a relatively small surface area, so the reverberation time is generally longer.
Possible Measures to Solve the Acoustic Defects of Stadiums
The acoustic flaws in stadiums usually include two problems: one is that the reverberation time is too long, and the other is that there are severe acoustic focusing and tremor echoes. The difficulty of solving the first problem is not too great. Just adding appropriate amount of sound-absorbing materials (using full use of the wall and the top) in the stadium can shorten the reverberation time. The technical difficulty is that the design calculation is accurate. The rigor of sex and construction process.
The major difficulty in solving the acoustic deficiencies of stadiums is how to eliminate the severe sound focusing and tremor echoes caused by arched domes and circular walls, without changing the overall shape of the museum’s original architectural design and decoration design. The appearance, lighting function and architectural style are the most challenging and creative keys in sound design.
Common solutions to the above problems are the following:
(1) Install a large-area flat sound-absorbing ceiling on the roof. This method is widely used in theaters, auditoriums, and flat-shaped gymnasiums. It works well. However, if it is used for arched domes or gymnasiums with translucent roofs, this method will completely destroy the original style and lighting function and is not desirable.
(2) Suspend a large area of ​​sound absorber under the arched grid. This method was used for the Beijing North City Stadium and the Guangzhou Zhongshan Memorial Hall. However, gymnasiums that are used for arched domes or light-transmitting roofing materials also affect the perception, but also affect the position of the originally designed or installed lighting fixtures that need to be changed and are not desirable.
(3) Install strip-shaped sound absorbers (sound absorbers) along the vault network. This method was used at the Guangzhou Stadium, the main venue of the 9th National Games. It uses German patented sound-absorbing strips, which are very expensive and expensive. , but the effect did not reach the ideal.
(4) Spray sound absorbing slurry (vegetal cellulose) to the dome. This method was used for the stage back wall and side wall surface of the Guangzhou Zhongshan Memorial Hall. The effect is acceptable and suitable for large-area and precise reverberation design.
(5) In recent years, the more common practice is to use pre-tested space absorbers (prefabricated parts), suspended along the roof of the rack in the shape of the rack, to achieve a relatively good and accurate sound absorption effect. Similar methods have been used for stadiums such as the Guzhen Stadium in Zhongshan, Guangdong, and Zhaoqing University Gymnasium. This scheme will not overly affect the architectural style. If the shape and color of the space absorber are properly combined and matched, there will be certain beautification effects.
The new features of sound design in the era of modern sports architecture:
The sound quality design mainly obeys and adapts to the architect's design and decoration pattern. The acoustic engineer has changed from the former consultant type to the challenge type.
The space for sports buildings is getting bigger and bigger, and there are fewer and fewer places where sound-absorbing materials can be arranged. Therefore, the first choice of materials is strong sound-absorbing materials and strong sound-absorbing structures.
The stadium has reverberation and no reverberation time. The past was partially covered. At present, there are canopies over the audience. In the past, the auditorium was completely empty behind the auditorium. It was now filled with conference rooms, reception rooms, and VIP rooms. It was completely closed. The enclosure structure.
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