Selection of Acoustic Design Schemes for Small and Medium Stadiums

This article will mainly introduce the basic knowledge of acoustic design of domestic small and medium-sized stadiums and acoustic design methods, and mainly analyze the advantages and disadvantages of different methods of sound reinforcement, and finally propose solutions.

The acoustic design of stadiums and stadiums has a commonality and personality. As far as the acoustic environment of the competition venue is concerned, the stadium is a closed acoustic environment and belongs to the indoor sound field. The stadium is an open acoustic environment and belongs to the outdoor sound field. This is the basic point of design choice.

With the vigorous promotion and development of China's sports industry and the continuous improvement of the people’s material living standards, domestic cities are building stadiums. Their scale is practical, multi-functional, and simple, and belongs to small and medium venues. For this part of the stadium construction should pay attention to, and technically correct and scientific norms and guidance. This article simply introduces the method of acoustic design for stadiums and does not design EASE software design.

体育场馆声学设计

1 Acoustic environment

1.1 Basic structure and orientation

The basic structure of small and medium-sized stadiums is open, open and closed. Usually, there is an open stadium with no function rooms under the seats.

The stadium is divided into a multi-purpose stadium and a special sports stadium. Most stadiums in China are now multi-purpose stadiums, which are suitable for competitions in various sporting events and ordinary theatrical performances. Special sports stadiums are designed and built according to the characteristics of a certain sport, and are only suitable for specific sports competitions, such as special football stadiums, bicycle competition fields, tennis courts, etc.

In China, the orientation of small and medium-sized stadiums is generally similar to that of train stations. It Faces south, that is, the rostrum is in the right position on the north side of the stadium hall. It meets all-weather lighting requirements. The sun is from the rostrum. Falling down on the right, the disadvantage is that the competition for sports such as football will be smooth and backlit, which is not conducive to fair play. Due to the limitation of the venue, there is also a seat on the west side of the stadium where the rostrum is located on the west side of the stadium. This orientation does not meet all-weather lighting requirements. The advantage is that there is no light and backlight for the sports events such as football. The difference is conducive to fair play.

Passage, the width of the playing field is 75M, the length is about 110M, the football field is 90M from east to west, and the north-south direction is about 65M. The basic layout of the stadium and the opening and closing stroke diagram of the athletes at the opening ceremony.

The seats around the stadium are saddle-shaped structures. For the stadium facing south to the south, the rostrum is located in the middle of the north stand, the north stand is about 32 to 35 seats, the south stand is also about 32 to 35 seats, the east stand is about 20 seats, and the background stand is behind the south stand. The torch stand is located on the east side of the podium, the timing and scoreboards are on the west side of the podium, and the west stand is also about 20 seats. For the stadium that sits west to the east, as long as the basic direction of the stadium facing south to the south will be rotated counterclockwise by 90°, you can get the basic map of the stadium and the opening and closing ceremonies of the athletes.

The setting and form of the stadium can be varied. In some stadiums, only pedestals are set above the podium; some stadiums are only equipped with sheds above the north and south stands; others also have stadiums (or activities) set up above the stadium in addition to the pedestals set up around the stands. Roof). There are no traffic lanes or stormy roads below the grandstand.

1.2 Problems and Solutions

The main problems commonly encountered in the design of acoustics for small and medium-sized stadiums are: severe multiple echoes, severe sound spillovers (disturbing), and more local silence zones (sound dead zones), which need to be coordinated and acoustically designed together with electro-acoustic design.

Multiple echo problems can be solved in two ways. First, in terms of sound design, we must increase some sound absorption and reflection surfaces to minimize the propagation distance of sound in space, increase sound absorption efficiency, reduce reflected sound energy, and avoid multiple reflections of high-energy sound sound waves. Longer reverberation radius. The second is to start with electro-acoustic design, choose a speaker with large directivity (Q value), narrow directionality, such as Q>15, horizontal directionality 60° to 90°, and even 40° to 20°, 40° The passband attenuation slope of ~20° is greater than 60° to 90°, and the acoustic energy outside the passband is much lower. It is also necessary to correctly design and adjust the speaker's coverage area and control the frequency bandwidth of the low-frequency sound, which can also receive some effects. Note that the narrower the speaker's directionality is, the higher the cost is, and the overall trade-off must be made.

Solve the problem of serious sound spillage (disruption), in addition to increase the sound insulation settings, but also correctly design and adjust the speaker's pointing and coverage area, in order to reduce the sound of spillover disturbance. Also choose a speaker with a large directivity factor (Q value) and a narrow covering angle.

The problem of the local silence zone (sound dead zone) can be solved by using a small power dispersion speaker.

Small and medium-sized stadiums are also worth noting in the acoustic design: if the major and minor axes are elliptical or arc segments, large diameter circles or arcs, large columns, whispering echoes, and other structures and walls, It is easy to bring about the effects of focusing, crawling, etc., causing severe sound defects, destroying sound quality, and reducing language intelligibility. To a certain extent, this is a contradiction between modeling design and aesthetic design. In the design process, we must pay close attention to and rationally coordinate the relationship between the two. There are three solutions: it is possible to start with sound design, try to avoid or reduce the appearance of the above structures and walls; or increase the sound absorption of the above structures and walls, and adopt strong sound absorption measures. This method will greatly Increased investment is not desirable; or a combination of the two. Which design scheme is adopted can be determined according to the size of capital investment.

2 sound reinforcement system

2.1 The use of sound reinforcement systems and sound reinforcement

The places where the sound reinforcement system is used include indoor, outdoor and indoor. The on-site sound reinforcement system covers venues, spectators stands, stormy traffic lanes, and checkpoints. The off-site sound reinforcement system covers functional venues outside the stadium, such as driving range and preparation fields. The indoor sound reinforcement system covers various functions. Room, VIP room, lounge, meeting room, athlete distribution center, corridors, etc.

There are three types of sound distribution systems: decentralized, centralized, and hybrid. The respective advantages and disadvantages are shown in Table 1.

Sound reinforcement program

advantage

Shortcomings

centralized

1, the layout of the speaker is similar to the location of the sound source is more accurate

2, the phase difference is small;

3, short pipelines, construction easier

4, easy installation, inspection and maintenance

5, power amplifier with constant resistance transmission, frequency bandwidth, good sound quality

1. The required sound power is large, the sound power loss rate is large, and the sound is easily spilled.

2. Picking the net rack must have enough load capacity, and the speaker hanging and pitching angle adjustment is difficult.

3. Speaker inspection and maintenance trouble

4. There are more dead zones in the auditorium

5. Difficulties in echo control

6. Large investment, high cost, low cost performance

7. There is a general audio and video position from the rostrum.

Decentralized

1. The required sound power is small, the sound is not easy to spill, and the interference to the outside is small;

2. Picking grid load is small

3. Speaker hanging and debugging, easy maintenance

4. There is no sound dead zone in the audience

5. Echo is easy to control

1. The layout of the speaker system is a dispersive sound source, and there is no general sound and image position in the sound.

2. There is a large time difference and there are sound disturbances in the area;

3. The power amplifier is transmitted with constant pressure, the frequency band is narrow, and the sound quality is poor;

4. Line transformers require high manufacturing processes, small distortion in performance requirements, and bandwidth.

5. Long pipelines, large construction volume

6. Low cost, high performance price

mixed type

If designed properly, hybrids can give full play to the advantages of centralized and decentralized, avoiding their shortcomings, which is a very flexible way of sound reinforcement.

In Table 1, the requirement for rough sound image position from the direction of the podium is not necessary for the stadium to invest a lot of money to ensure accurate sound and image position, as long as the sound can be basically required to ensure good speech intelligibility. Sound coverage is even.

With distributed sound reinforcement, the sound comes from two directions or multiple directions. The time difference is large. The sound interference in the adjacent area must be controlled so that the sound system coverage area is reasonable so as not to affect the sound clarity. Speakers can not be placed opposite to avoid combing effect. Speaker's directivity requirements; high Q, high sensitivity, and strong sound transmission.

Domestic sound systems and equipment, regardless of performance, reliability, sound quality, timbre, etc., can fully meet the system support, use requirements and functional requirements of small and medium-sized stadiums, high performance and price ratio, and convenient maintenance and quick maintenance. The author believes that when the designers are designing, users should use a large number of domestically produced products when they are supporting the selection, and actively support the development of China's professional audio products industry.

Let's talk about the selection principles of the sound reinforcement system when we perform mobile theatrical performances in small and medium stadiums. The sound reinforcement system for mobile theatrical performances may be selected for imported products, and domestic equipment may be used for fixed installations. For example, excellent sound quality speakers and special vocal microphones can be used for targeted selection of imported products. Mixers and their peripheral equipment are all optional domestic products, and power amplifiers do not need to use imported products.

2.2 sound reinforcement system design example

The design of stadium sound reinforcement system mainly includes two major parts: the layout of loudspeakers and the configuration of system equipment.

It is better to use a hybrid array mode. The sound field diagram is made by computer EASE software. The layout of the speaker requires the designer to select an approximate location and then finalize it with computer software. Take the east-west stadium as an example. A sound-producing area is set up in the center of the playing field, and each area of ​​the north and south stands is supplemented with a sound-filling area to design speaker coverage and control systems. The central supporting area for the game field and the north and south stands for the sound area are key guarantee areas for sound quality, sound level, and sound field non-uniformity. The rostrum belongs to the category of VIP areas, whether it is designed individually or not, depending on the design ideas and capital investment.

The center of the field is made a sound area, covered with 3 groups of speakers, and hung on the north stand to pick up the sheds, with the role of sound and image control. For the north and south stands, the audience zone uses five groups of speakers to hang on the north and south stands to pick up the shelves and cover the north and south stands. Two sets of speakers were used in the audience stands of the East and West stands. One group was hung on the edge of the north stand.

Areas where half of the audience, half of the walls of the audience, and obstacles are not covered by the sound of the back surface can all be covered with separate, smaller speakers to make up the sound.

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