Guangdong Institute of Science and Technology Gymnasium
I. Overview of The Acoustic Project Case of The Gymnasium of Guangdong Institute of Science and Technology
Picture 1 Exterior View of The Gymnasium
Guangdong Institute of Science and Technology Gymnasium is a small and medium-sized comprehensive gymnasium. The gymnasium is divided into two areas, the competition hall and the stage. Its main functions are cultural performances and sports competitions and gatherings. The construction base area is about 2,190 m², the effective volume of the competition hall is about 41,800 m³, the total indoor surface area is about 12,070 m². It possesses 1,828 fixed seats. The top surface is the grid structure color steel plate roof, the shape of it is a rectangle, the surrounding wall and the top surface are parallel to the ground. In order to ensure the normal use of the venue, the venue environment requires appropriate language clarity and certain reverberation to guarantee to provide a good listening experience to the spectators.
Ⅱ. The Site Survey Before The Architectural Acoustic Design of The Project Case of Guangdong Institute Science And Technology Gymnasium
In the early stage, the owner of the gymnasium did not understand the importance of acoustics and failed to make the acoustic design of the gymnasium. After the completion of the construction, the sound in the gymnasium was blurred and has serious acoustic defects with a large echo, which was difficult to meet the functional requirements of the gymnasium. The designers performed an acoustic test on the site and the test results are as follows:
Figure 2 Survey Point Distribution Map
Table 1 Stadium Reconnaissance Empty Field Reverberation Time Value
According to the test results, the intermediate frequency reverberation time of 500 Hz reaches 11.6 s, 1000 Hz reaches 10.9 s. That indicates that the reverberation time is too long, and the echo is too large, which can not meet the various functions of the gymnasium.
Ⅲ. The Design Goal of The Acoustic Project Case of The Gymnasium of the Guangdong Institute of Science And Technology
The goal of architectural acoustic design is to make the sound and voice clear and beautiful when the gymnasium is in
use. According to the “Architectural Design Code for Gymnasium” (JGJ31-2003; J265-2003), the reverberation time of the gymnasium’s full-field intermediate frequency (500 Hz) should be 1.5-1.7 s. After the conversion of the number of people in the gymnasium, the empty-field intermediate frequency (500 Hz) reverberation time should be around 2.0 s. The low-frequency reverberation time is allowed to be slightly longer, while the high-frequency reverberation time is allowed to be slightly shorter. The characteristics of reverberation time frequency in the empty field are shown in Table 2. According to the gymnasium design rules, the indoor background noise limit of the gymnasium competition hall and other rooms is shown in Table 3.
Ⅳ. The Sound Field Analysis of The Acoustic Project Case of The Gymnasium of Guangdong Institute of Science And Technology
1. The gymnasium has a volume of 41,800 m³, and each volume reaches 15 m³/person. It is very easy to generate echo and multiple echoes, which makes people listen to the turbid voice.
2. The competition area has a length of 39 m and a width of 31 m. The free sound path is too large and it is easy to produce echoes. Especially when holding small meetings, the echoes are obvious for the small number of people in the hall.
3. The competition area is rectangular with parallel walls. It is easy to produce a vibrating echo between parallel walls.
4. The ceiling of the gymnasium is a parallel roof, which is easy to form multiple reflections with the parallel
floors. The above phenomena will cause the gymnasium to produce sound defects, affecting the listening effect of athletes and audiences. Acoustic materials must be properly installed to improve and eliminate acoustic defects.
5. The ceiling of the gymnasium is a steel structure, and the material bulk density cannot exceed the ultimate load value of the steel structure.
V. The Acoustic Design Scheme for The Acoustic Engineering Case of The Gymnasium of Guangdong Institute of Science And Technology
Since the competition field usually has hardwood floors, it will have a strong reflection effect on the sound waves. Therefore, the ceiling is arranged with materials or structures with strong sound absorption properties to avoid echo interference. According to the original design of the gymnasium, the space absorber is arranged under the top rafter with the full consideration of sound quality requirements of the gymnasium.
5.2 Wall Surface
The wall is an important part of the stadium’s architectural design. In order to avoid having a monotony and rigid style of the walls, the walls of the gymnasium hall are designed to use the slotted and perforated acoustic structure according to the original design of the gymnasium. It is modern, simple, generous and has a relatively flat sound absorption characteristic in the entire frequency band.
Due to the limited budget of the first party, it can only make sound processing on the walls which affect the sound field. Therefore, it is recommended to install slotted acoustic panels on the rear wall of the auditorium, the both-side walls and the wall of the competition field. The total installation area is 1300 m².
According to the scene, a large number of glass windows are installed on both sides and the back wall of the gymnasium’s audience hall. The glass surface is smooth, which is very likely to produce a vibrating echo and then seriously affects the indoor sound quality. Therefore, it is recommended that the site must be equipped with curtains with strong sound absorption properties.
Ⅵ. The Acoustic Design Effect of The Acoustic Project Case of The Gymnasium of Guangdong Institute of Science and Technology
6.1 Beautiful and elegant decoration, good visual comfort.
6.2 Sound-absorbing materials are free of dust pollution caused by glass fiber particles, no formaldehyde pollution, and can meet the environmental requirements of air quality in the site.
6.3 It has good sound quality. That is, the low, medium and high notes are moderately balanced.
6.4 Sound-absorbing materials can meet the fire rating requirements.
6.5 The sounds in the venue are clear without sound quality defects such as silent dyeing.
6.6 After the implementation of the project, the acoustic environment and the on-site environment are appropriate, and the reverberation time of the site can reach the national standard C standard.
Ⅶ. Acoustic Decoration Effect of The Acoustic Project Case of the Gymnasium of Guangdong Institute of Science and Technology
After the renovation of the architectural acoustics, it basically meets the functions of the gymnasium. The indoor effects are as follows:
After acoustic modification, the acoustic performance test on site is carried out. The test results are as follows:
On-site Acoustic Test Results
According to the on-site test results, the average frequency of reverberation time of 500 Hz is 1.84 s, and the average reverberation time at 1000 Hz is 1.97 s. Under the same conditions, the value of medium frequency 500 Hz-1000 Hz reverberation time is 2.0. The deviance between actual data and design data does not exceed 10%, and the deviance is within ±0.15 s, which can meet the original design requirements. After acoustic treatment,
effectively eliminates acoustic defects such as echo, multiple echoes, and tremor echo. The sound spread in the gymnasium is clear and it can meet the requirements of national standards.
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