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The main functions of a theater building are sightline and acoustics. The visual effects are relatively easy to solve because there are rules to follow. However, good acoustics effects involve the effects of many factors such as human physiology and psychology, which is more difficult. If a theater wants to achieve good sound quality and effects, it requires close cooperation from many parties. Not only careful acoustic design is required, but also reasonable operating procedures are required.
The acoustic design of theaters is divided into two stages: civil engineering and interior design (small theaters are usually completed by the civil engineering department at one time). Civil engineering design mainly determines the preliminary concept of body shape and interface materials, which is related to important indicators in acoustic design – loudness (volume), early reflection sound, sound diffusion, uniform distribution of sound field and elimination of sound quality defects, etc.
Therefore, obtaining the basic guarantee of good sound quality is the key to acoustic design. The task of the interior design stage is to correct the deficiencies in physical design in civil engineering design and control the reverberation time. At the same time, it is necessary to achieve the combination of acoustic function and artistic effect, so that it can achieve perfect artistic effect while obtaining good sound quality.
The shape of the auditorium of the theater so far includes the traditional horseshoe-shaped multi-layered box shape and various shapes suitable for the needs of modern life.
1. The shape of the traditional theater
The traditional theater shape has great vitality, and a considerable number of theaters still use this form today. The reasons are as follows:
(1) The horseshoe-shaped with multi-layered boxes theaters place a large number of audiences in the multi-layered boxes, thereby shortening the distance between the back row audience and the stage. The audience can obtain sufficient loudness (volume), which is the most important factor in the acoustic design of the theater because opera singers do not receive acoustic support from the stage when singing, part of the sound energy is absorbed and escapes. In addition, the singing sound must also penetrate the “sound wall” formed by the accompaniment of a three-pipe or two-pipe band in the orchestra pit in front of the stage to reach the auditorium, it is crucial to save and make full use of limited natural sound energy to ensure sufficient loudness in the auditorium. This is also the fundamental reason why the traditional horseshoe-shaped multi-level box has such great vitality.
(2) Multi-layered boxes evenly distribute a large number of audiences on the interface of the enclosed space, that is, they are the main sound absorbers in the theater (the sound absorption of the audience and seats usually accounts for 70 to 80% of the total sound absorption) Distributed on multi-layer walls to obtain uniform sound field distribution.
(3) Due to the baroque luxurious interior decoration of the auditorium of the traditional theater, it not only has good sound diffusion and eliminates sound quality defects, but also creates an atmosphere for the audience to appreciate traditional opera.
- The horseshoe-shaped theaters surround the actors among the multi-layered audiences, enhancing the emotional communication between the actors and the audience.
Therefore, the traditional body shape is still widely used today. The main problems with the shape of the traditional theater are the large depression angle of the upper box and the front area of the side seats, poor visual effects, small row spacing and narrow seat width, which cannot meet the audience’s comfort requirements. Therefore, how modern theaters inherit the excellent qualities of traditional theaters and correct their shortcomings is the key to mastering the design of theaters.
In the design of modern theaters, the first breakthrough in the traditional theater horseshoe-shaped multi-layered box form was the Hamburg Theater in Germany built in the 1950s. It adopted a polygonal shape and dropped boxes on both sides, which improved the high-rise boxes and side boxes.
The modern horseshoe shape has transformed the traditional horseshoe shape. It still uses the horseshoe shape, but appropriately reduces the number of side boxes. Some have drop boxes to expand the seating capacity by increasing the length and width of the audience. There are many examples in this regard. Typical examples are the Metropolitan Opera in New York and the Sydney Opera House.
Metropolitan Opera in New York
Sydney Opera House
The modern shape is completely different from the traditional horseshoe-shaped multi-layered box body shape. It has various forms: rectangular, polygonal, circular and oval, etc. Generally, there are two to three floors of seats and drop boxes. The interface is equipped with a diffusion structure and various treatment measures to provide early reflection sound.
Advantages and disadvantages of architectural acoustics of different floor plans:
- Horseshoe shape fan shape
Advantages: Most of the audience is within the directional coverage of singing and musical sounds.
Disadvantages: long sight distance and weak direct sound for the back rows, and most seats lack early reflections from side walls.
- Bell shape
Advantages: Most of the audience have a good viewing angle and are within the directional coverage of singing and musical sounds.
Disadvantages: The audience in the back rows will be far away from the stage and the direct sound intensity will be reduced.
- Polygonal shape(inverted sector)
Advantages: The pool-seat auditorium obtains a large coverage of lateral early reflection sound.
Disadvantages: The structure is relatively complex.
What to consider to get a good architectural acoustics design?
- Characteristics
* Reverberation time meets the requirements of different functions
* Diffuse sound field
* Good clarity
2) Main indicators
Reverberation time (RT): 1.2～1.6s;
Warmth BR: 1.1～1.15;
Intensity factor G: 3~5dB;
Clarity C80 (sound energy ratio): 0~-2dB;
3) Key points of architectural acoustic design
* The building shape and wall decoration form should have good diffusion
* Set up the reverberation adjustment device
* Set up sound reflection panels on the stage
* Decoration materials must be calculated and configured
- Multifunctional implementation for adjustable reverberation device and sound reflection panels on the stage
- Adjustable reverberation devices as:
* Curtain-type reverberation adjustment structure
* Louver-type reverberation adjustment structure
* Rotary reverberation adjustment structure
* Lift-type reverberation adjustment structure
- Sound reflection panels on the stage
* Make full use of limited natural sound energy (singing or musical instruments) to prevent sound energy from escaping and being absorbed on a huge stage
* The space inside the cover becomes a continuation of the auditorium, eliminating sound quality defects caused by the coupling between the stage and the auditorium
* Make the players hear each other in time so that the players can correctly grasp the intensity and speed and achieve the balance and harmony of the performance;
* Improve the uniformity of the sound field in the auditorium
* Increases the early reflected sound in the front and middle seats of the hall, shortens the initial delay gap, and increases the intensity of direct sound, thus improving the sense of intimacy
* Improve the reverberation time in the auditorium
How to conduct acoustic design in theaters and concert halls?
The detailed processing and the furnishings of the theater hall and interior play a very important role in the sound quality effect, so they cannot be ignored. Detailed processing includes the proscenium entrance of the theater auditorium, the railings of the balcony and boxes, the ceiling under the balcony and the acoustic treatment of the back wall, etc. The concert hall has the interior design of the bandstand, including band steps, pipe organs and suspension relevant decoration treatment of reflectors, etc.
- Stage opening of theaters and multi-purpose halls
The stage opening of theaters and multi-purpose halls plays an important role in obtaining early reflected sound from the front and middle seats in the hall. The reflective surface formed by the side walls and the roof in front of the stage should be designed to obtain reflected sound in the front and middle areas of the pool seat, which cannot be replaced by other interfaces in the hall.
- Balcony and box railings
Theaters usually have to take into account both natural sound and sound amplification performances. The sound source is located at two different locations: the stage (natural sound) and the sound bridge above the proscenium (speaker group of the sound amplification system). The balcony railings are usually It is a concave arc shape. Therefore, the fence should be designed with diffusion, and the form can be convex arc-shaped circular noodles, triangles, cones, etc.
- The ceiling under the balcony
The seats under the balcony are usually far away from the stage. In order to obtain a uniform sound field distribution, under the conditions of natural sound performance, the ceiling should play the role of enhancing the sound intensity of the back seats; when sound amplification is used, the ceiling should make the speaker group sound smoothly entered the space under the balcony.
- The back wall of the auditorium
The decoration of the back wall of the auditorium should be based on the use of function and performance methods of the hall. For concert halls and theaters with natural sound performances, the back wall should be processed for sound reflection and diffusion. For halls with sound reinforcement systems, sound-absorbing structures can be used to prevent echoes.
- Decorative finishes of the speaker group
The veneer structure of the speaker set in the auditorium must meet both sound transmission and aesthetic requirements.
(1) The facing structure must have the greatest possible sound transmittance, which shall not be less than 50%;
(2) The speaker lining cloth should be as thin as possible to avoid affecting the output of high-frequency sound;
(3) The structure must have sufficient stiffness to prevent resonance.
(4) When using wooden grille veneer, the width of the wooden strips should not be greater than 50mm to avoid blocking the output of high-frequency sound.
6. Use sound-absorbing and sound-insulating cotton for inorganic fiber spraying, it is economical and cost-effective, and the price is much lower than traditional sound-absorbing materials and sound-insulation materials. It is directly sprayed on ceilings, glass, steel pipes, walls, etc. of complex structures. The construction is simple, perfectly integrated with the original pattern of the building, and greatly reduces the construction time. What’s more important is that there are a variety of colors to choose from, completely in line with the designer’s design style, or in terms of sound absorption, sound insulation, fire resistance, etc. Sound-absorbing cotton and inorganic fiber spraying has unparalleled advantages over traditional acoustic materials, achieving the owner’s original intention of upgrading the sound effect.
