HC sound lighting network reported a basic sound field design process include sound insulation, reducing on-site noise, structural requirements, to achieve sound and evenness of sound vibration, focus and feedback to avoid problems, and so on indoor calculation, the following classification shall be analysis.
To give a similar example: everyone knows the relationship between the speaker unit and the cabinet in the speaker. Many people have come back to the famous foreign speaker unit including the crossover, but they can't make a good speaker anyway. The main reason is that the acoustic structure of the cabinet is not solved. The design of the sound field in professional sound engineering is as important as the design of the cabinet. The design of a good sound field is as important as the design of the cabinet. The sound field will fully play the advantages of audio equipment, which makes people sound very comfortable, and an unreasonable sound field will not only give people a wonderful sound experience, but also reduce the performance level of the equipment. Of course, due to the construction The level of decoration and the user's understanding of the degree of sound engineering, many projects are very late to contact the sound construction unit, so that the sound field design can not be completed, and the sound field design must rely on architectural decoration to achieve, so a large number of sound engineering is In the absence of sound field design is essential, and only the sound design and construction unit Sub recognizing the importance of the sound field design, available allowing users to recognize its importance.
A basic sound field design includes sound insulation processing, site noise reduction, building structure requirements, sound uniformity to achieve acoustic tremor, focus, feedback and other issues to avoid, indoor calculations, etc., the following classification for analysis.
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(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 the sound field design, the sound insulation should be considered first to provide a good innate condition for the sound field. The sound insulation involves the construction. Sound insulation with the outside world, sound insulation of each room in the building; sound insulation parts include: sound insulation of the partition wall, sound insulation of the doors and windows, and sound insulation of the ceiling of the room connected to the top.
For the sound insulation with the outside world, the general building structure can achieve the basic sound insulation requirements, but if the architectural design does not consider the need of sound engineering at all, it is necessary to conduct an investigation of the sound insulation, and if necessary, should design the building. The unit conducts consultations and knows the local noise restrictions from the public security organs. Usually do not use the height of the floor as sound insulation for the sound insulation between the rooms. If the wall is too thin, it will bring some difficulty to the project. This time, in consultation with the decoration unit, add a layer to the wall during decoration. Intermittent to solve the high and medium frequency sound insulation.
It is more difficult to completely solve the sound insulation of the low frequency band, because there is no other more effective way to increase the weight of the sound insulation. Doors and windows are the weak link of the sound insulation treatment. For their sound insulation, it can be recommended to the decoration unit. Improve the quality of the production of doors and windows, if necessary, the use of leather doors and double-glazed windows, or the addition of isolation channels outside the door and the thick double-layer curtains hanging on the windows, etc., is also the key to the ceiling of the ceiling room. Especially in some large-scale entertainment venues built in recent years, the sound of the hall has a great influence on the surrounding rooms. Some of the disturbances are from the top of the ceiling. This part of the sound insulation scheme cannot be raised too late, otherwise it is difficult. Implementation, so the sound designer is required to ask the decoration unit as soon as possible to coordinate a feasible solution, such as: covering the ceiling with a layer of fire-resistant sound-absorbing cotton or adding a layer of ceiling at a certain distance above the ceiling, etc. In short, engineering The sound insulation treatment is of great significance, which not only improves the quality of the project but also facilitates the normal use of the user. Carefully consider the acoustic treatment is necessary, the processing method is feasible, otherwise it will increase the number of unnecessary work and expense.
(2) Reduction of on-site noise
For the background noise of the scene, many people do not pay attention to it, but in the relevant national standards, they all put forward corresponding requirements, such as: the first-level karaoke should be less than 35dB, the first-level disco should be less than 40dB, the reason is: the increase of background noise The large corresponding reduction of the signal-to-noise ratio of the sound reinforcement system affects the quality of the project. To effectively solve this problem, the above-mentioned sound insulation is limited, for example, whether the air-conditioning noise of the central air conditioner allows the installation unit to help solve the problem; The noise, size, installation location, etc.
(3) The situation of the building structure
It should be said that the general sound is not capable of letting the building structure completely designed according to its own intentions. However, for the part where the engineering quality requirements are strict and the construction engineering is processed on the reconstructed structure, it is necessary for the sound designer to make corresponding requirements as much as possible. The optimum proportion of the length, width and height of the structural part, the shape of the wall, and the position setting of the control room have already been mentioned in the overall planning of the front. Here, some architectural partial structures related to the engineering installation are mainly mentioned here. In the first case, the building unit must first obtain the recognition of the load-bearing capacity of the wall or roof of the sound engineering that needs to be hoisted equipment. Especially when the weight of the light shed is large, the safety of hoisting is more important. Secondly, it needs to be The structure of the room in the building, the location of the pre-buried pipeline, and the exit have a more detailed understanding to facilitate the possible insertion of the pipe and wiring, and then to understand the weak links of the internal structure of the building, to find out what landlord can change, what No place.
(4) Realization of sound uniformity
The concept of sound uniformity is generally not very clear, and there is not much consideration in the project. Is it not important, right? No, not only important, but also very important. For example, if you go to an entertainment hall, you will find that the sounds in different places are different. Some places are very beautiful. Some places are like shortcomings. The sound is erratic. Another example: the front stage area is very loud, while the audience behind it says that the sound is small (of course, some entertainment halls are designed to make the back area easy for the audience). These phenomena are all caused by poor uniformity. In the standard, it is based on the concept of sound field inhomogeneity. It is generally required that the field pressure level test value deviation is less than 2dB at each point. How to achieve a uniform sound field? First of all, there should be no obvious defects in the building structure. For example, there should not be too many columns in the room, and the walls should avoid trapped arcs, especially the wall on the side of the stage should not have a large structure; Large acoustic shadow areas appear in the interior, but since a large number of changes cannot be made to meet these requirements after the completion of the construction of the building structure, it is necessary to use the experience in the sound engineering to skillfully arrange the sound reinforcement area and avoid the comparison. The large defect structure minimizes the impact of them; secondly, it can provide some simple solutions for improving the sound diffusion effect to the decoration unit in time and effectively. For example, all concert halls have good sound diffusion effects. It is a sound diffuser with a large variety of shapes inside, and these structures can be completed by some simple decoration methods, so as long as the method is appropriate, it can achieve better results, of course, the shape, position, It is not easy to make a reasonable and appropriate design. It is generally economically feasible to use a wall. The method of mud pulling, although this method is relatively old and not very beautiful, but it can play a very effective role in the sound diffusion of the hall, in addition, the sound system is arranged reasonably, especially the position of the speaker must be Strict requirements, if you can use the computer design software provided by some speaker manufacturers to simulate the sound field in the design, it is better, if not, it should be adjusted in practice until the sound field is the best.
(5) Avoidance of acoustic vibration, focus, and feedback
For the problem that the sound vibration, sound focus, and sound feedback bring poor sound reinforcement, some people can only say that the sound effect is not good, and all of them are classified as equipment. This is not appropriate. In fact, they should all belong to the sound field. Category, usually these problems do not happen from time to time, so in general engineering, often can not attract enough attention, even if these problems occur, many people do not realize that this is caused by the unreasonable sound field, or that is known as the sound field The hospital is unreasonable and there is no way to solve it. For example, the sound system work is generally normal, but occasionally a rhythmic pulse-like sound or "squeaky" sound can be heard on the spot. Usually it is most likely to occur in some places in the middle and low frequency bands. When the hall is large, the sound is separated from the direct sound for a long time, which makes people feel very uncomfortable. This is a kind of tremor. The reason is that the sound is relatively parallel in the hall. The walls are reflected back and forth, and the reflection of the wall is very strong, so the sound energy is hard to be weakened. Therefore, it is required to check whether there is any in the hall at any time during the decoration. Two large reflective areas with strong reflexivity, there are not too many glass, stainless steel structure, because these things that seem normal in the decoration unit may cause problems; the arc surface of the sound focus occurs Xuan some large decorative items or hanging curtains, curtains, etc., to reduce the possibility of acoustic focusing; pre-prevention of acoustic feedback is more difficult, and the design can not accurately predict the frequency of feedback, but the prevention of acoustic feedback The practical application is more important, so it is possible to analyze the sound absorption coefficient at different frequency points when designing the decorative materials in the early stage of the design, and refer to the calculation of the reverberation time to make a rough judgment, which provides the necessary reference for construction and debugging. In order to completely solve the above problems in many aspects, it is necessary to improve the equipment debugging in the later stage. Generally, after the completion of the project, the signal generator and the spectrum analyzer are used to detect the sound reinforcement area, and the equipment is repeatedly debugged to make up. The lack of sound field.
(6) Calculation of reverberation time
For the sound field design, the average person can understand intuitively, and the more contact is the reverberation time, because it is the most controllable quantitative indicator in the design. The importance of reasonable reverberation time is reflected in the design. The sound field will make the sound system perform very well, giving the impression that the sound is full and round, not dragging, and not disturbing. It can be said that if the requirements of the sound field design in the front can be satisfactorily satisfied, the reverberation time can be controlled. If you are good, you can add a lot of sound effects. You must first choose a reasonable reverberation time target value before calculation. The selection of this value is generally based on the volume and purpose of the hall.
On the specific value, most designers prefer to make the recommended sound field reverberation time smaller. The reason is: the sound field reverberation time can not be adjusted after a long time, so it is suggested that the hall should be more natural. The better, the better, in the debugging and use, the artificial reverberation is added to the system to meet the reverberation requirements. At the same time, in recent years, the interior decoration materials are increasingly updated, and the materials with higher sound absorption coefficient are widely used, which makes the mixing of a large number of halls. The ringing time is generally small. It can be seen that the starting point of this design principle and the influence of objective conditions are not doubtful, but it should be known that the reverb sound in the sound field is the natural reverberation produced by the sound source. It is based on direct sound to show its particularity. It is an important characteristic in the sound field. When the system is used, artificial reverberation is added, which is equivalent to the direct sound of the signal and the reverberation. In the sound that is played, there is no direct sound that the sound engineer wants you to hear, although the recording will usually add different levels of reverberation, which is equivalent to destroying the source. Sound source), so this method not only disturbs the good relationship between the direct sound and the reverberation sound, but also violates the sound field reverberation in order to make the room have the proper "canyon" purpose, which I think can be put forward For engineering design sales staff to discuss.
The brief reverberation time is calculated as follows:
General engineering can be carefully calculated at home at 500 Hz or kHz. The sound absorption coefficient of various materials should be strictly in accordance with the data provided in the product parameters or the building materials manual. Otherwise, the calculation results may be larger and larger, of course, with the recommended values. Based on the near calculation results, the designer does not need to ask the decoration unit to improve too much, because the reverberation time requirement is not a specific absolute value, as long as the disparity is not too large, the calculation should also consider the audience. The effect on reverberation time.
(7) At the end of the sound field design, the calculation of sound pressure level should also be considered.
The purpose is not only to provide users with feasible engineering electroacoustic parameters, in order to facilitate their safe and correct use of equipment, to create a healthy listening environment, but also to provide a basis for electrical design in sound engineering. The selection of the model provides a reference.
Before calculating the sound pressure level, it is necessary to select a corresponding appropriate environment for its quasi-sound pressure level, and the selection of the reference sound pressure level must understand the equal-acoustic curve of the normal human ear, namely the Fletcher-Munson curve.
The curve reflects the human ear's response to different frequencies and different sound pressures. The numbers on the curve indicate the corresponding frequencies and loudness values ​​under sound pressure. The unit is: Phono, the human ear's sound with different frequencies of the same sound pressure. The response is not the same. The sound level of the low-frequency sound of the same sound pressure level in the human ear is lower than the high-frequency sound of the same sound pressure level; if the sound of each frequency band is basically the same in the human ear, In the absence of hearing in certain frequency bands, it is necessary to achieve a sound pressure level of sound pressure, which is the basis for selecting the sound pressure of the sound pressure.
For the language sound reinforcement project, since the language signal is mainly concentrated in the middle frequency band, the equal response curve degree is less correlated here, so the reference sound pressure level can be 70~80dB; for the sound engineering of general music playback, this reference sound The pressure can take 85~90dB as the basis for calculation; at the same time, leave the peak of 12~18dB peak and the ambient noise margin of 1~3dB for the sound reinforcement of the system, then the rated spread of the design on the average listening distance The sound pressure level should be: P = (85 ~ 90) dB + (1 ~ 3) dB and then the average listening distance L needs to be determined according to the actual sound range of the hall. The rated sound pressure level should be at this position. The actual sound pressure level, and then the sound pressure level P of the 1m position of the speaker can be calculated by:
According to the above mentioned: the distance change is doubled and the sound pressure changes by 6dB. The sound pressure level that the speaker needs to provide at 1m is: P=P amount +6LogL. The design of the sound is basically finished, and the subsequent work is completed. It is to work closely with the building decoration unit to put the design requirements into practice.
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