Among them, the positioning of the project should be based on the principle of seeking truth from facts, not pursuing unrealistic high-grade and fancy, nor ignoring important functions that affect the quality of the project;
The sound construction of the hall should follow the principle of making the sound equipment play the best effect in the corresponding environment. This work is of great significance and can best test the level of designers. These requirements will be discussed later.
The requirement of architectural decoration should be based on the principle of architectural sound and light efficiency; The target positioning of sound and lighting should be based on giving full play to the equipment performance, so as to achieve the goal of beautiful sound quality and good light efficiency;
The safety and rationality of the project and its impact on the environment should be based on the principle of strictly observing the laws and regulations of relevant state departments, especially the safety and fire prevention, rational use of electricity and avoidance of environmental pollution. The determination principle of master plan is analyzed. If you want to implement the master plan well, you must consider everything comprehensively, that is to say, you should consider all the factors involved in the project and clear the obstacles for the subsequent construction in the preparatory work before construction, but you can't affect the progress of the master plan because of some small considerations. Therefore, the overall planning needs technicians with rich design experience.
(1) engineering orientation
Engineering positioning is what users want to know most. Most users need to know what features this design has, what level it can achieve, or more specifically, whether this project can reach or exceed a project he is familiar with. Therefore, designers should fully understand their own design ideas and clearly understand the performance of equipment. For example, the project has certain requirements for the performance effect, and your design should tell the other party what design configurations are considered for the performance, such as how to arrange the stage lighting; In the design, there is not much room for improving the sound effect, and when the possibility of improving the lighting effect is still great, you should also explain to the other party how your design is adjusted.
(2) the hall building sound
Most sound projects are carried out in the hall, and the overall quality of the hall is related to whether the equipment performance can be effectively exerted, especially the sound construction of the hall has a great influence on the sound effect, so this work should be done honestly no matter what the conditions are, and the result will be very favorable. First of all, the structure of the hall should try to avoid standing waves. According to the normal frequency formula, that is, the proportion should be an irrational number, so that the normal frequency distribution can be uniform, thus effectively avoiding the generation of standing waves. Some halls are specially designed for sound engineering alone, and sound technicians can put forward corresponding requirements as soon as possible; For the reconstructed hall, it is necessary to get in touch with relevant personnel before the reconstruction begins, and put forward the architectural requirements for sound field construction in time. Here are some ratios of length, width and height of halls that can effectively avoid standing waves (L, W and H in the same group can be interchanged).
Secondly, in order to ensure better sound reinforcement effect and lighting projection area, we should try our best to ensure the highest internal space height of the hall. Some projects did not fully consider the requirements of acoustic lighting when they were selected, and the hall of several hundred square meters was less than 3 meters high. It is conceivable that the acoustic lighting effect here will not be very good. Moreover, in order to avoid acoustic vibration, try to make the walls slightly non-parallel, especially in long and narrow halls, and pay more attention to wall treatment. In order to avoid the influence of sound focusing on sound reinforcement gain, the curved wall should be treated as much as possible, at least not used as a stage. Finally. In order to make the operation more simple and convenient, we must pay attention to the setting of the control room. Because many projects do not take into account the wiring of the project, the placement of equipment, the operator's vision and other factors, the control room is either very small or completely isolated from the hall, leaving some regrets for the project, so we should pay attention to the following points:
1, the space of the control room should be as large as possible, and the specific size can be determined according to the number of cabinets and the number of staff. Generally, 7~ 10 square meter is more suitable;
2, the location of the control room should be conducive to the laying of pipelines, and the power supply should be more convenient, especially for some large discos, whose consoles are set at high places or in the middle of the hall, which requires the coordination of architectural decoration parts to create harmonious conditions for the construction of sound engineering;
3, the control room should be able to keep good contact with the outside world, which is conducive to a good observation of the outside world. In some projects, the control room is completely isolated from the site or only a small window communicates with the site, which makes it impossible for the operator to grasp the sound and lighting conditions of the site. In many cases, the adjustment of sound is only carried out through headphones, which brings great inconvenience to the work and is also very unreasonable, because the headphone listening room can know the signal situation in the equipment. However, due to the excellent sound field, large number of people and even the change of atmosphere, the on-site meeting needs to adjust the sound differently, especially the volume, which needs the operator to know very well. If the control room is too isolated from the site, it will easily lead to misjudgment by the operators. He didn't know that the scene was small, and he didn't think it was enough when the scene was large. As for whether the control room should be located on the same side of the stage or at the other end of the stage, it depends on the actual situation and cannot be generalized. In general, the control room can be located on the same side of the stage to keep in touch with the actors. When there are many entertainment or on-site lights, the control room should be located at the other end of the stage as far as possible, so as to observe the atmosphere, demand and lighting work of the scene well.
(3) the requirements of architectural decoration
For sound engineering, reasonable architectural decoration will bring very favorable conditions to the project. Therefore, before architectural decoration begins, the design and coordination of sound engineering must be carried out. If the overall decoration scheme has been determined or even the decoration project is about to be completed, the design and construction of the sound engineering can not be effectively coordinated, which requires the sound technicians to put forward the requirements of the building decoration for the sound engineering as soon as possible.
Morality is the key requirement of architectural decoration. Many people don't understand this, so it is difficult to get their approval. At the same time, it is likely to conflict with the building decoration department. Therefore, we must be careful to make reasonable and easy demands. In fact, the color of architectural decoration will affect people's intuitive understanding of sound engineering to a certain extent, and the effect will affect the performance of lighting, so we should pay enough attention to it. For general versatility, especially when used for meetings or performances, it should not be too dark because of the color tone. For performance venues, we should consider the color of the decorations on the stage. For entertainment discos, we should refer to the opinions of lighting design in the color of ceiling and floor, because most computer lights and effect light are generally reflected in the air and floor, and the color of ceiling and floor is related to whether these beams and patterns can be well set off.
Secondly, the requirements of architectural decoration tickets, architectural decoration projects will make their own choices in terms of materials because of cost, structure, construction feasibility and other factors, but for the requirements of sound engineering, some tickets often have a negative impact, so we should also put forward relevant requirements. Materials that have a great influence on the sound field of the hall must be guaranteed, for example, the data difference caused by different perforation rates of sound-absorbing perforated plates will be great; Use hollow building materials as little as possible; Materials with high reflectivity should not be used on walls and so on.
Furthermore, there are requirements for architectural decoration technology. It should be said that the general building decoration technology will not affect the sound engineering, but some small links will still bring hidden dangers to the sound field if they are not handled well. For the requirements of acoustic engineering, it is necessary to resolutely avoid using cavity structures with large hollowness or poor support in the sound reinforcement area, otherwise, it is easy to produce * * * vibration and noise, and the source and frequency of these noises are difficult to find, even if they are found. There must be many floor support points on the stage or dance floor, and the floor space of the dance floor should not be too high. It should also be noted that the installation of ceiling and glass must consider vibration reduction, otherwise the vibration generated by these decorative materials will be very uncomfortable when they work at a high volume, especially in the bass area, so generally do not use large-area glass windows, do not directly install gypsum ceiling in aluminum alloy tanks, and rubber pads should be added.
(4) Targeting of lighting and sound.
Many effects, characteristics and styles of sound engineering are subjective, especially for users who are not familiar with sound lighting, they can only guess the final actual effect of the project, and it is difficult for them to locate the project objectives. However, the target positioning of the project is very important for the style and investment of the project, which requires careful consultation between the two parties.
On the premise of fully respecting users' opinions, the style positioning of the project should let the other party know as much as possible the function and overall style of the system after the project is completed with a frank attitude. Never add some unnecessary functions just because you want users to raise costs to meet a so-called "high-end requirement". You should implement practical solutions for users with a realistic attitude, so as to gain the good trust of the other party. Only in this way can the project satisfy the users. If the top equipment is used up blindly, it is not only difficult to form a unique style, but also the equipment is too complicated, resulting in poor use effect. And low cost does not necessarily mean that the quality of the project is not high. This should be clear to users. On the premise of ensuring a certain style, we should also reasonably grasp the proportion of sound and light in project investment, and the target positioning of the project often needs to be realized through this proportion. With regard to proportion, it should be noted that the general acousto-optic engineering first considers the acoustic effect and function, and only on this premise, it is necessary to put forward requirements for the effect and grade of lighting. This is the view of most people and the actual response of human senses, because people's basic requirements for sound effects are far higher than those for lighting effects; On the other hand, when the sound effect reaches a certain level, it will be more difficult to improve the sound quality than the lighting.
The relationship between these two aspects is applied to practical projects: for projects with low cost or high requirements for sound, first consider working hard on sound, and then use appropriate funds on lighting; For high-grade projects or formal performance venues, after ensuring a certain acoustic level, the first consideration is the upgrade of lighting, because the change of lighting grade will be very prominent in the eyes of ordinary people. If you want to improve the audio quality, you will often increase your investment several times, and the effect may not be recognized by ordinary people. For example, the equipment investment ratio of multi-function halls and entertainment centers for internal use can adopt acoustics: the lighting is 2.5: 1.5, 2.5. As a business sound, the lighting is 1: 1:1.5, 1: 2, 1: 3 or even higher. Of course, the specific proportion depends on the function of the project and the experience of the design salesman.
(5) The safety and rationality of the project and its impact on the environment.
Because it is a master plan, all aspects of the project must be considered, including the safety of the project and its impact on the environment. The safety of engineering is often ignored by people, and its importance is only discovered when it always happens or encounters trouble. For sound engineering, safety involves both design and construction. The safety of the design includes: whether the power distribution is reasonable, whether the power consumption is safe, whether the equipment connection is scientific, whether the load bearing is guaranteed, and whether the wiring is correct. Safety in construction includes: whether the equipment installation is firm, whether debugging will damage the equipment, make the project unqualified and endanger personal safety. Therefore, designers must not ignore the importance of safety, and the impact on the environment is mainly the interference of noise to surrounding residents and units. As users, they consider this problem before the project is completed, and the design and sales staff are technicians with practical experience. At the same time, we have a better understanding of the corresponding projects. If I explain the situation to the other party in time before the project starts or during the construction, and provide necessary rectification measures, I believe the cooperation between the two parties will be smoother. For a similar example, everyone knows the relationship between the speaker unit and the box in the sound box. Many people buy famous original speaker units including frequency dividers from abroad, but they can't make good-looking speakers anyway. The main reason is that the acoustic structure of the box has not been well solved. The design of sound field in acoustic engineering is as important as the design of box when making sound box. When making a speaker, a good sound field design is as important as the design of the box. A good sound field will give full play to the advantages of audio equipment and make people feel very comfortable, while an unreasonable sound field will not only bring people a wonderful sound experience, but also reduce the performance level of the equipment. Of course, due to the limitation of building decoration level and users' understanding of sound engineering, many projects are contacted with the sound construction unit very late, and the sound field design cannot be completed. The sound field design must be realized through building decoration. Therefore, it is essential for a large number of sound engineering to lack sound field design. Only when the sound design and construction unit fully realizes the importance of sound field design, users can realize its importance.
A basic sound field design includes the treatment of sound insulation, the reduction of field noise, the requirements of building structure, the realization of sound uniformity, the avoidance of vibration, focusing and feedback, indoor calculation and so on. , according to the following categories.
(1) Sound insulation treatment
In order to create a quiet sound field and avoid affecting the units and residents in the surrounding environment, at the beginning of sound field design, sound insulation treatment should be considered first to provide good congenital conditions for sound field. Sound insulation treatment involves the sound insulation between the building and the outside world and the sound insulation of all rooms in the building. The sound insulation part includes: partition wall sound insulation, door and window sound insulation, room ceiling sound insulation with communication at the top, etc.
For sound insulation from the outside world, the general building structure can meet the basic sound insulation requirements. However, if the architectural design completely ignores the needs of acoustic engineering, it is necessary to investigate the sound insulation situation, consult the architectural design unit if necessary, and ask the public security organs about the local noise restrictions. In general, the height of the floor should not be used for sound insulation between rooms in sound engineering. If the wall is too thin, it will bring some difficulties to the project. At this time, it is necessary to negotiate with the decoration unit to add a layer of sound insulation to the wall during the decoration to solve the problem of sound insulation at medium and high frequencies.
Low-frequency sound insulation is difficult to completely solve, because there is no more effective way except to increase the weight of the sound insulation body. Doors and windows are the weak link of sound insulation treatment. For their sound insulation, it is suggested that the decoration unit improve the quality of doors and windows, use leather doors and double-layer glass windows when necessary, or increase isolation passages outside the doors and hang heavy double-layer curtains on the windows. This is also very important for the sound insulation of the ceiling of the room communicating with the top. Especially in some large entertainment places, the acoustics of the lobby have a great influence on the surrounding rooms, and some interference comes from the ceiling. This part of the sound insulation scheme can not be put forward too late, otherwise it will be difficult to implement. Therefore, audio designers are required to ask questions to the decoration unit as soon as possible and coordinate feasible schemes, such as covering the ceiling with a layer of fire-proof sound-absorbing cotton or adding a layer of ceiling at regular intervals. The sound insulation treatment of this project is of great significance, which not only improves the engineering quality, but also benefits the normal use of users. At the same time, we should carefully consider whether the sound insulation treatment is necessary and whether the treatment method is feasible, otherwise it will increase some unnecessary work and expenses.
(2) the reduction of noise at the scene
Many people don't pay attention to the background noise of the scene, but they all put forward corresponding requirements in the relevant national standards, such as: the first-class karaoke hall should be less than 35dB, and the first-class disco should be less than 40dB. The reason is that the increase of background noise correspondingly reduces the signal-to-noise ratio of the sound reinforcement system and affects the engineering quality. In order to effectively solve this problem, the above sound insulation should be limited, such as whether the installation unit can help solve the tuyere noise of central air conditioning; Noise, size and installation position of exhaust fan, etc.
(3) the situation of the building structure
It should be said that the general sound system is unable to design the building structure completely according to its own intention. However, in the case that the quality of the project is strict and the building project belongs to the reconstructed structure, it is necessary for the sound designer to put forward the corresponding requirements as far as possible, in which the optimal ratio of the length, width and height of the structural part, the shape of the wall and the position of the control room have been mentioned in the previous master plan. This paper mainly talks about some local structures of buildings related to engineering installation. First of all, the bearing capacity of the wall or roof that needs hoisting equipment in audio engineering needs to be recognized by the construction unit, especially in the case of heavy light shed, hoisting safety is more important; Secondly, it is necessary to have a detailed understanding of the room structure, embedded pipeline location and exit in the existing building, so as to facilitate the possible construction of intubation and wiring. In addition, we should also understand the weak links in the internal structure of the building and find out what the landlord can and cannot change.
(4) Realization of sound uniformity
The concept of sound uniformity is generally not very clear, and there is not much consideration in engineering. Is it not important? No, not only important, but also very important. For example, if you go to an entertainment hall, you will find that the sound conditions in each place are different. In some places, the music is beautiful, and in some places, it seems that there are shortcomings and the sound is erratic; For example, the front stage area is loud, but the audience at the back says it is low (of course, some entertainment halls are specially designed to let the audience at the back relax). These phenomena are all caused by poor uniformity. In the relevant national standards, the concept of sound field inhomogeneity is used to express it. Generally, the deviation of sound pressure level test values at each point is required to be less than 2dB. How can we achieve uniform sound field?
First of all, the building structure cannot have obvious defects. For example, there should not be too many columns in the room, and the walls should avoid the arc of traps, especially the walls on one side of the stage should not have large structures; There can't be a large sound shadow area within the sound reinforcement range, but a lot of changes can't meet these requirements after the building structure decoration is completed in the later stage of construction, so we should make full use of our experience in acoustic engineering, skillfully arrange the sound reinforcement area, avoid large defective structures and minimize its influence;
Secondly, we can provide some simple solutions to improve the sound diffusion effect to the decoration units in time and effectively. For example, the sound reinforcement effect of all concert halls is very good, because a large number of loudspeakers of various shapes are used inside, and these structures can be completed by some simple decoration methods, so as long as the methods are proper, good results should be achieved. Of course, it is not easy to design the shape, position and number of diffusers reasonably and appropriately. Generally, the more economical and feasible way is to use the method of wall cement roughening. Although this method is old and unsightly, it can play a very effective role in the sound diffusion in the hall. In addition, the sound system should also be arranged reasonably, especially the placement of speakers. It would be better if computer design software provided by some speaker manufacturers can be used to simulate the sound field in the design. If not, it should be adjusted in practice until the sound field reaches the best.
(5) Vibration avoidance, focusing and feedback.
As for the poor sound reinforcement effect caused by acoustic vibration, acoustic focusing and acoustic feedback, some people can only generally say that the acoustic effect is not good, which is not appropriate. In fact, they all belong to the category of sound field, and usually these problems don't always exist, so they often can't attract enough attention in general projects. Even if these problems occur, many people don't realize that they are caused by unreasonable sound field. Or we just know that the sound field is unreasonable and there is no way to solve it. For example, the sound system works normally, but occasionally we will suddenly hear rhythmic "flapping" or "buzzing" sounds at the scene, which are usually most likely to occur somewhere in the middle and low frequency bands. When the hall is big, this kind of sound is far away from the direct sound, which makes people feel very uncomfortable. This is called acoustic tremor.
The reason is that the sound is reflected back and forth between the relatively parallel walls in the hall, and the walls are highly reflective, so it is difficult to weaken the sound energy. Therefore, it is required to check whether there are two large reflective parallel planes in the hall at any time during decoration, and whether there are too many glass and stainless steel structures, because these common things for decoration units may lead to problems; Put some large decorative items or hang curtains, curtains, etc. on the arc surface where acoustic focusing occurs. Reducing the possibility of acoustic focusing; It is difficult to prevent acoustic feedback in the early stage, and it is impossible to accurately predict the frequency of feedback in the design, but it is very important for practical application. Therefore, when selecting decorative materials in the early stage of design, we can analyze their sound absorption coefficients at different frequency points and make a rough judgment with reference to the calculation of reverberation time, which provides necessary reference for construction and debugging. Of course, to completely solve the above problems, it can only be improved by later equipment debugging. Generally, signal generators and frequencies are used after the project is completed.
(6) Calculation of reverberation time
Most people can intuitively understand the sound field design, and reverberation time is the most controllable quantitative index in the design. The importance lies in: if properly designed and the reasonable reverberation time is reflected on the sound field, the sound system will perform very well, giving people the impression that the sound is full and round, without procrastination and interference. It can be said that if the requirements of the previous sound field design can be well met and the reverberation time can be well controlled, the acoustic effect will be enhanced. A reasonable reverberation time target value must be selected before calculation, generally according to the volume and use of the hall.
In terms of specific values, most designers tend to make the recommended reverberation time of the sound field smaller, because the reverberation time of the sound field is too long to control, so it is suggested that the natural sound of the hall should be as dry as possible, and artificial reverberation should be added to the system to meet the requirements of reverberation during debugging and use. At the same time, the increasingly updated interior decoration materials and the extensive use of materials with high sound absorption coefficient make the reverberation time of a large number of halls generally smaller. Obviously, the starting point of this design principle and the influence of objective conditions are beyond doubt, but we should know that the reverberation sound in the sound field refers to the natural reverberation sound produced by the sound source, and it is an important feature in the sound field to show its particularity by setting off the direct sound. When the system is used, adding artificial reverberation is equivalent to adding direct sound in the signal to the reverberation, and then playing it out by the loudspeaker. There is no direct sound that the sound engineer wants you to hear. Although different degrees of reverberation are usually added when recording programs, it is equivalent to destroying the program source (sound source). Therefore, this method not only disturbs the good contrast between direct sound and reverberation, but also violates the purpose that sound field reverberation makes the room have the "hall sound". I think this point can be raised for discussion by engineering design salesmen.
The simple formula for calculating reverberation time is as follows:
General engineering at home 500Hz or kHz can be carefully calculated. The sound absorption coefficient of various materials should be strictly in accordance with the data provided in product parameters or building materials manuals, otherwise the calculation results may be quite different. Of course, for the calculation result close to the recommended value, the designer does not need to ask the decoration unit to improve it too much, because the requirement of reverberation time is not a specific absolute value, as long as it is not too large, and the influence of the audience on reverberation time should also be considered in the calculation.
(7) At the end of sound field design, the calculation of sound pressure level should also be considered.
Its purpose is not only to provide users with feasible engineering electro-acoustic parameters, help users use equipment safely and correctly, and create a healthy and hygienic listening environment, but also to provide basis for electrical design in audio engineering and provide reference for equipment selection.
Before calculating the sound pressure level, it is necessary to choose the corresponding and suitable environment, and the reference sound pressure level must be selected by understanding the equivalent curve of normal human ears, that is, Fleche-Munson curve.
This curve reflects the loudness response of human ears to different frequencies and sound pressures. The number on the curve represents the loudness value at the corresponding frequency and sound pressure, and the unit is Phono. Human ears have different responses to sounds with the same sound pressure and different frequencies. The loudness perception of low-frequency sounds with the same sound pressure level in human ears is lower than that of high-frequency sounds with the same sound pressure level. In order to make the loudness of different frequency bands basically the same in human ears, and there is no lack of hearing in some frequency bands, it is necessary to make the sound pressure reach enough sound pressure level, which is the basis for selecting reference sound pressure in sound pressure calculation.
For the project of language sound reinforcement, the reference sound pressure level can be 70 ~ 80 dB, because the language signal is mainly concentrated in the middle frequency band, and the equal response curve here has little correlation. This reference sound pressure can be used as the basis of calculation for the sound engineering of general music playback. At the same time, there is a peak margin of 12~ 18dB and an environmental noise margin of 1~3dB for the sound reinforcement of the system, so the designed rated sound pressure level of sound reinforcement should be: P =(85~90)dB+( 1~3)dB according to the hall.
According to the relationship mentioned above that the sound pressure changes by 6dB when the distance is doubled, the sound pressure level that the speaker needs to provide at 1m is: P=P quantity +6LogL, so the sound design is basically over, and the subsequent work is to closely cooperate with the building decoration unit to implement the design requirements.