With the successful bidding and closure of the Beijing Olympics, Guangzhou Asian Games, and Shenzhen Universiade in China, there has been a wave of construction and renovation of sports buildings in various regions. In recent years, first, second, and third tier cities in China have been planning and constructing sports centers, comprehensive gyms, swimming pools, gyms, sports venues, and other sports buildings. On the other hand, some old sports venues urgently need to be renovated and renovated due to their inability to meet new usage needs, which has driven the rapid development of China's cultural and economic construction. While people pursue material and spiritual civilization, the demand for sports facilities is also constantly increasing, This has put China in a peak period of sports development.

Since 2008, the Acoustic and Theater Special Design and Research Institute of the East China Urban Architectural Design and Research Institute (hereinafter referred to as the "East China Institute of Acoustics") has undertaken the architectural acoustic design of more than 20 sports venue buildings, covering sports centers, comprehensive gyms, swimming pools, tennis courts, training centers, etc. The scale and quantity of the projects have greatly improved compared to previous years, and more attention has been paid to the acoustic design of sports buildings, Technical requirements are also constantly improving. Especially many sports venues require multifunctional usage requirements. In addition to meeting various basic competitions such as basketball, volleyball, handball, table tennis, badminton, and gymnastics, they also have the functions of using various large-scale concerts, variety shows, music performances, and conferences. This can bring greater economic benefits and social recognition, but it puts forward more requirements for the sound environment design of sports venues, Suitable reverberation time, no acoustic defects such as echoes, uniform sound field distribution, and sufficiently low background noise. Therefore, in the design and construction process of various sports building projects, it is necessary to pay attention to the above acoustic requirements and carry out necessary architectural acoustic design.

Technical Essentials of Acoustic Design for Gymnasium Buildings

Controlling Reverberation Time and Avoiding Sound Defects

Nowadays, architects often pursue "high, large, and unique" in creating architectural appearances, which is also reflected in sports architectural design. Large volume, high space, circular, egg shaped and other venues with different body shapes are everywhere, and the control of reverberation time and the design of avoiding sound defects in the acoustic environment of sports venues are particularly crucial, which brings many difficulties to the acoustic design. The design indicators of reverberation time are inevitably related to the volume of the venue and the individual volume. In the national industry standard (JGJ/T131-2012 Code for Acoustic Design and Measurement of Sports Venues), clear requirements for the design of intermediate frequency reverberation time are proposed for gymnasiums with different volumes. In the past decade, the acoustic design data of sports building engineering practices undertaken by me for acoustic design shows that 80% of large venues with a volume of over 80000m3 account for, Sports venues with a single person capacity greater than 20m3/person also account for about 70%. Some sports venues even have a single person capacity of over 30m3/person, which is not very reasonable for reverberation control, sound absorption area, and air conditioning energy-saving.

After determining the appropriate reverberation time and frequency characteristics for the sports stadium, attention should also be paid to avoiding sound defects such as focusing and vibrating echoes caused by circular and parallel walls in the venue. The usual solution to the poor shape of these buildings' flat sections is to use sound diffusers in combination with indoor decoration design, thereby changing the appearance of the original circular and parallel walls of the building, making the sound field in the venue more uniform. The form of sound diffusers can be designed into various forms by combining indoor decoration and sound absorption treatment, such as folded lines, triangles, arcs, cones, and even irregular shapes. The arrangement can be orderly or disorderly, and the covering materials can be perforated metal plates, wood striped boards, soft fabric sound-absorbing boards, or gypsum boards,GRG boards, etc. that play a diffusion and reflection role, which not only enriches the indoor decoration style, It can also make the sound field more uniform and achieve satisfactory acoustic effects.

Design of Noise and Vibration Control for Gymnasium Buildings

Appropriate background noise is the foundation for achieving sound quality design, and it is also an important part of the professional design of sports venue acoustics. The industry standard of the People's Republic of China (JGJ/T131-2012 Code for Acoustical Design and Measurement of Sports Venues) provides a basis for designing and determining the background noise of sports buildings. The general principles of the standard have proposed that architectural sound design should be involved in the entire process of sports hall engineering design. Therefore, it is required that the architectural acoustics profession should participate in the initial design stage of the building and provide sound and vibration isolation design for the building. In the layout of building profiles, equipment rooms with high noise and vibration such as air conditioning rooms and refrigeration rooms should be located away from the competition hall, and sound insulation and absorption treatment should be carried out inside the room, as well as unit vibration isolation design.

Silencing Design of Air Conditioning Systems

In order to achieve the pre designed background noise indicators, the noise reduction design of the air conditioning system is even more crucial, mainly including reducing the fan noise propagating along the pipeline (reasonable configuration of mufflers, silencing elbows, silencing static pressure boxes, etc.) and reasonable control of airflow noise. The fundamental measure to control airflow noise is to reduce the wind speed inside the air duct. In the book "Technical Measures for HVAC Design", based on years of design practice experience of HVAC professionals in China, the allowable values of airflow speed inside the pipeline under different allowable noise conditions are proposed, which can be referenced by relevant designers such as HVAC when designing air conditioning systems.

Top sound-absorbing design

Due to the increasing spatial volume of newly built sports buildings, the total sound absorption required in the hall also greatly increases. Usually, the walls that can be treated with sound absorption in sports venues are very limited. In order to control reverberation, it is necessary to take sound absorption measures at the top of the stadium. Since the 1980s, the top sound absorption method of many sports venues in China has been to combine the bottom chord of the grid or hang a certain form and quantity of spatial sound absorbers in the grid space. In order to meet the A-level fire protection requirements of the top material, the structure is mostly made of light steel or plastic, aluminum skeleton, centrifugal glass wool sound absorption layer, and perforated aluminum alloy board surface layer.

In recent years, in the interior decoration of sports venues, people's aesthetics have gradually tended to be simple and atmospheric, and sound-absorbing roofs have emerged and been widely used in various sports venues. Sound absorption roofs actually integrate sound insulation and absorption. These types of structures are mainly designed for medium to high frequency sound absorption, with an NRC value of 0.75 (500Hz-2KHz). It not only has good sound absorption effect, but also has the effect of insulation and isolating rainwater impact noise, and has been widely used.

In a swimming competition venue, if a sound-absorbing roof is designed, the impact of high humidity inside the venue on the sound-absorbing material inside the roof should be considered. An additional layer of PVF weather resistant bag can be added to wrap the sound-absorbing material, which can enhance its weather resistance and have limited impact on the sound-absorbing performance.

Wall sound absorption design

The wall area that can be sound-absorbing treated in the gymnasium is not large, and the wall area of the circular flat gymnasium is only the wall behind the last row of the audience, and the height is also very small; In addition to the wall behind the main stand, there are large sound-absorbing walls around the scoreboards at both ends of the rectangular plane gymnasium, so the main sound-absorbing capacity is the roof ceiling and audience seats.

Usually, the reverberation frequency in the gymnasium is basically flat (allowing for a certain increase in low-frequency). The sound absorption layout of the wall should consider the ratio of low-frequency sound absorption to medium and high-frequency sound absorption. After calculating the sound quality, it should be combined with indoor decoration design to achieve a win-win situation of functionality and aesthetics.

In recent years, in the form of sports buildings, more and more glass curtain walls have appeared around the competition hall, even forming a coupled space. This is extremely unfavorable for controlling the reverberation inside the hall. The vibration and echo generated by the reflection of sound through the glass will directly affect the acoustic environment of the competition hall and even affect the normal use of electrical and acoustic equipment if no measures are taken. The sound absorption measures studied and adopted by the Institute of Acoustics of East China Academy were to design and install electric sound absorption curtains in front of glass curtain walls, which automatically lowered to increase the sound absorption area during competition, and raised to meet the normal indoor lighting requirements during non competition. Figure 3 shows the interior rendering of the Yancheng Gymnasium in Jiangsu.

Suggestions on Acoustic Decoration Design of Gymnasium Buildings

In the state of competition in the gymnasium, people's attention is focused on the central area of the venue, so the decoration design of the gymnasium should focus on functionality, and the decoration effect should be atmospheric and concise. It is not advisable to use reflective materials such as glass, stone, and mirrors as interior decoration surfaces to avoid the visual impact on athletes during competition. The diffusion shape on the wall should not be too complex, it can meet the functional requirements to control the project cost.