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The installation of the main ribs for the exterior wall wooden panels also involves certain knowledge. Although the process is not very complicated, each step requires precise positioning.  First, it is necessary to inspect the wall where the wooden brackets will be installed to ensure it is level and clear any obstacles on the wall. Identify the horizontal reference line for installing the wooden brackets and mark it. This is to facilitate the installation of the keels. Then, we need to arrange and fix the keels. The keels are usually made of 50# lightweight steel material, or 2.5*3 cm square wood can also be used. The vertical distance from the keels to the ground should be 60 cm, and then use steel nails or expansion screws. The keels should be made of anti-corrosion materials (preferably those treated specially), and the keels around doors and windows should be laid to enhance stability.  Starting from the first layer at the bottom, use shot nails to fix the exterior wood hanging boards onto the keel. If using self-tapping screws, pre-drill holes with a twist drill. The nail heads should sink 0.5-1 millimeter into the wood. The bottom position should be treated for anti-corrosion. Then, apply putty to smooth it out. The distance between the nail holes and the board surface should be no less than 1.2 centimeters, usually 1.5 centimeters, and 2 centimeters at both ends. Repeat this process to fix the second and third wood hanging boards, and so on. When the width of the wall exceeds the length of the wood hanging boards, the interface at the same horizontal line should be on the keel and should not be connected in an unsupported manner.  The interface of the exterior wall wooden hanging boards should have a 3 to 5 millimeter gap. After that, the gap should be filled with adhesive. The inner and outer corners of the wooden hanging boards should naturally come together, leaving an appropriate gap. The top wooden hanging board should be bonded with sealant at the connection with the top eave to achieve a waterproof effect. When installing the wooden hanging boards at the doors and windows, they should be cut to match the shape of the doors and windows for installation to avoid through seams (which are prone to causing water leakage). The connection at adjacent wall corners should be sealed. Outside the wooden hanging boards, clean up the dust and stains, and apply a layer of acrylic paint.

The soundproof room integrates modern manufacturing industry, construction engineering, acoustic technology, and aesthetics. It is an environmental protection equipment designed to improve and control the increasingly serious noise pollution. It is commonly used in places with quiet requirements. What kind of soundproof products do you need? This varies from person to person. Soundproof products come in many types but can generally be classified into the following categories: 1. Industrial soundproof and noise reduction equipment: such as various soundproof rooms, soundproof chambers, soundproof covers, etc. These devices are targeted, such as noise reduction for cooling towers, large water pumps, boilers, and generator sets. These are mainly designed and developed to improve environmental noise. 2. Medical soundproof type: mainly refers to various soundproof and noise reduction projects in the medical field for working or conducting tests, research, etc. in special quiet environments, such as audiometry rooms, speech rooms, control rooms, etc. (The details are beyond the scope of this text.) 3. Civil architectural acoustic type: mainly includes various theaters, cinemas, conference halls, sports venues, recording studios, and studio rooms. 4. Popular type: various dance halls, soundproof windows, soundproof doors, partitions, etc., which are common soundproof and noise reduction products for the general public. 5. Other types: such as wood fiber sound-absorbing panels, metal sound-absorbing panels, mufflers, pipe sound absorption, vibration prevention devices, etc.

The construction industry and high-rise buildings have promoted the use of lightweight walls. In many high-rise buildings, there are often many companies or units occupying one or several floors. This determines that the space layout cannot be designed in a fixed pattern, and the flexibility of lightweight walls precisely meets the diversity of objective needs. At the same time, using lightweight walls can also reduce the weight of the building. However, the poor sound insulation performance of lightweight walls has always been a major obstacle to promoting their use. Generally, the average sound insulation of lightweight walls is about 30 dB, which is difficult to be used as partition walls. In the past, the partition walls of brick-concrete structure residential buildings were mostly 240mm thick brick walls, and their average sound insulation was about 53 dB, and the residents were generally satisfied.  To enhance the sound insulation performance of the lightweight walls, the following measures can be taken: 1. Construct a sandwich structure. That is, use porous elastic plant sound-absorbing materials to spray and compact them. For example, a lightweight wall structure with double-layer 12mm thick gypsum boards, steel keels, and 75mm hollow space filled with ultra-fine polyester fiber insulation on both sides, the average sound insulation can reach 49dB, while its unit area mass is only one-tenth of that of a 240mm thick brick wall. 2. When the thickness of the air interlayer is reduced to more than 5mm, the sound insulation can be increased by 8-10dB in most frequency bands. For example, a lightweight wall structure with 75mm thick aerated concrete boards on both sides and 75mm air space, the average sound level can reach 50dB. Filling the air interlayer with new stage sound-absorbing materials can increase the sound insulation by 2-8dB. 3. To avoid the matching effect of the lightweight walls, the quality of each layer of materials can be different to avoid the matching valley. 4. The tightness of the board joints of the lightweight walls has a significant impact on sound insulation. For double-layer boards, the joints should be staggered. For single boards, they should be plastered or jointed. For each single board, whether to apply jointing or not can differ by 12-17dB. When setting recessed electrical switch boxes and socket boxes on both sides of the three-sided wall, the positions of the settings on both sides should be staggered, and the surrounding gaps should be filled properly.

Nowadays, sound-absorbing panels are used in many places, such as TV stations, concert halls, conference centers, stadiums, shopping malls, hotels, theaters, libraries, hospitals and various other venues. The ubiquitous sound-absorbing panels bring us a lot of convenience in our daily lives.  When it comes to home decoration, wooden sound-absorbing panels are mostly used. They are meticulously processed based on acoustic principles and consist of a decorative core material and sound-absorbing thin felt. Wooden sound-absorbing panels are divided into two types: slot wood sound-absorbing panels and hole wood sound-absorbing panels. Generally, the wooden sound-absorbing panels used in homes are mainly hole wood sound-absorbing panels. They achieve sound absorption through the numerous tiny interconnected pores inside the material, which allow the sound waves to penetrate deep into the material and interact with the material, converting sound energy into heat energy, thereby achieving thin plate resonance sound absorption. As a result, the thin plate vibrates vigorously and absorbs a large amount of sound energy. At the same time, as the frequency increases, the sound absorption coefficient gradually increases, meaning that high-frequency absorption is better than low-frequency absorption. Eventually, it meets the sound absorption requirements. In addition, it can also improve the sound quality and enhance the clarity of speech. Journalists have learned from the building materials market that according to the needs of different consumers, the decorative surfaces of sound-absorbing panels include various solid wood veneers, painted surfaces, imported lacquered surfaces, etc. They can be selected based on the different styles of the home. At the same time, according to the actual situation of the owner, sound-absorbing panels can be decorated at specific locations to achieve both aesthetic and practical effects, and play a role in reducing noise in the home.  In addition, there are various types of sound-absorbing panels, such as fabric sound-absorbing panels, mineral wool sound-absorbing panels, aluminum honeycomb perforated sound-absorbing panels, metal sound-absorbing panels, and polyester fiber sound-absorbing panels. Different sound-absorbing panels are suitable for different application scenarios, and the requirements for sound absorption effect are naturally different as well.

The porous material sound absorption structure refers to a sound absorption structure that is specifically formed by using the loose raw materials of porous materials as the basic sound absorption material and through structural design. It absorbs sound by directly exerting the sound absorption characteristics of the porous sound absorption materials. Such sound absorption structures fully apply and demonstrate the sound absorption performance and application value of the porous sound absorption materials themselves.  Porous materials such as fibrous porous sound-absorbing materials or granular porous sound-absorbing materials have their raw materials in the form of loose fibers or granular loose materials. Although they all have excellent sound-absorbing properties, these raw materials cannot be directly placed in the sound-absorbing space required without any modification. Instead, a specific sound-absorbing structure needs to be designed, and the porous materials should be placed within it to prevent the loose materials from scattering. Although this treatment may have some impact on the original sound-absorbing ability of the materials, both practice and theory indicate that the impact is not significant. Basically, it does not reduce the sound-absorbing performance of the materials themselves, and the sound-absorbing characteristics of the porous materials can still be fully exerted. This is the sound-absorbing structure of porous materials described in this chapter.  Over the years, a relatively mature, standardized and commonly used porous material acoustic absorption structure has been formed in acoustic design. The main construction forms include the following. However, these construction forms are not the only ones, because with the development and innovation of acoustic technology, new materials and new designs of acoustic absorption structures will continue to be developed.

In recent years, complaints from urban and rural residents regarding noise pollution in social life have significantly increased, posing new demands on the response capabilities of environmental law enforcement agencies and personnel. How should we deal with social life noise pollution?    The environmental noise pollution as defined in Article 2 of the "Law on the Prevention and Control of Environmental Noise Pollution" (hereinafter referred to as the "Noise Law") refers to the phenomenon where the generated environmental noise exceeds the national standards for environmental noise emission and interferes with the normal life, work and study of others.    That is to say, there are two conditions for noise pollution: one is the objective reality of excessive emissions, and the other is the psychological perception factor that affects the normal life of residents. For the former, it lies in the strict comparison of emission standards and monitoring values; while for the latter, due to the characteristics of noise pollution and the emotional state of the victims at that time, it is difficult to capture the scene and even more difficult to define.    The "Noise Control Law" (established in 1996) stipulates that the departments responsible for managing the prevention and control of noise pollution in social life include the environmental protection administrative department, the cultural administrative department, the industrial and commercial administrative department, and the public security department, etc. Among them, the ones with the power of administrative penalties are the public security department and the environmental protection administrative department. However, no attention has been paid to people's individual needs.    In my opinion, as long as there are phenomena of noise pollution in social life that disturb residents, according to Article 7 of the "Noise Control Law", any unit or individual has the right to report and accuse the units or individuals that cause environmental noise pollution. Regarding civil liability, according to Article 61 of the "Noise Control Law", the parties have the right to request that the environmental protection administrative department or other departments or institutions responsible for environmental noise pollution prevention and control mediation and handle disputes over compensation liability and compensation amount. For administrative liability, relevant functional departments should clarify the situation, resolve disputes, and handle them properly in accordance with the law.    First, based on the source of the noise, determine the regulatory entity, applicable provisions, and penalties.    For social life noise coming from fixed places, facilities or equipment, the environmental protection administrative department shall, in accordance with the provisions of Article 59 of the "Noise Control Law", order rectification and may impose a fine.    Regarding social life noise from other sources, the public security authorities will apply the "Noise Law" based on the specific circumstances. Specifically: noise emanating from car horns, sound systems, and renovations (during the completion and use period) shall be subject to Article 58 of the "Noise Law", which states: (1) Using high-pitched audio equipment in areas with concentrated noise-sensitive buildings in urban areas; (2) Organizing entertainment or gatherings in urban streets, squares, parks, etc. in violation of the regulations of the local public security authorities, using audio equipment to generate excessive volume that interferes with the surrounding living environment; (3) Failing to take measures as stipulated in Article 46 and Article 47 of the "Noise Law" to emit severe environmental noise that seriously disturbs the lives of surrounding residents; the public security authorities shall give a warning and may impose a fine. For occasional intense noise, Article 54 of the "Noise Law" stipulates that in violation of Article 19 of the "Noise Law", that is, conducting activities that generate occasional strong noise without the approval of the local public security authorities, the public security authorities shall, depending on the circumstances, give a warning or impose a fine. Additionally, Article 60 of the "Noise Law" stipulates that in commercial activities, using high-pitched audio equipment or adopting other methods that emit high noise to attract customers, causing environmental noise pollution, shall also be ordered to correct by the public security authorities and may be fined (the second paragraph of this article is determined based on the circumstances of each province).    Second, the environmental protection authorities are responsible for unified supervision and management. There are numerous types of social life noise, and it is difficult for laws and regulations to enumerate all the regulatory provisions. However, Article 6 of the "Noise Law" stipulates that the environmental protection administrative department of the local people's government at or above the county level shall implement unified supervision and management of environmental noise pollution prevention and control within its administrative region. The responsibilities of relevant functional departments are both divided and have their own focuses, cooperating with each other, either directly handling or guiding complaints. Among them, the environmental protection department is the unified supervisor, but it is by no means in charge of everything or in charge of all, nor does it cover all aspects.    The environmental protection department has the responsibility to explain to residents the relevant regulations on social life noise, guide them to report violations, and resolve disputes; for complaints that comply with the law but do not fall within the jurisdiction of this department, it should inform the applicant to submit the complaint to the relevant administrative agency.

Sound insulation materials work by using their impedance to reflect sound waves, resulting in very little transmission of sound in the area covered by the insulation material. On the other hand, sound absorption materials achieve an infinite sound field through their absorption structures and media, thereby reducing reflected sound waves. The application of these two types of materials has different requirements. Simply substituting one for the other may not meet your technical specifications and could even have the opposite effect.  A more practical example would require the application of the theory of sound field modeling for analysis, using some related equations to solve it. Take what you mentioned as an example. If sound-absorbing materials are used in a concert hall, the hall is originally designed to balance the reflected sound field and the infinite far-field. Appropriate sound-absorbing materials are used to eliminate unnecessary reflections and achieve a purposeful reverberation field. However, if sound-absorbing materials are replaced with soundproof materials, the sound that was intended to be weakened is reflected back, causing a change in the reverberation field. This might result in the music you hear being a loud buzzing sound, and it persists constantly. Generally, in a concert hall, sound-absorbing materials are selected based on the architectural structure, main function, and desired effect of the hall, and they are designed to absorb and weaken sounds at different frequencies. These are the main purposes of architectural acoustics.  The situation regarding the use of sound-absorbing materials along the railway is as follows. First of all, let me clarify that sound-absorbing materials do not mean completely eliminating the sound; instead, they consume the energy of sound waves at certain frequencies. However, sound waves at other non-absorbing frequencies can still pass through the material. Railway noise has a wide range of frequencies and a large amount of energy from the source. If only using general sound-absorbing materials, the effect would be negligible. Behind the set sound-absorbing materials (usually in residential areas), there is still a lot of noise. And sound insulation materials are generally reflective materials; they can almost completely reflect the incident sound waves back.  Of course, in terms of special design, the noise reduction on the railway side can also be achieved by using sound-absorbing materials. Human hearing is sensitive to noise at certain frequency ranges. By taking advantage of this, it is possible to set up the absorption of sound waves at these frequency ranges to achieve the effect of eliminating noise. The most commonly used methods are probably pure reflection and a combination of the two. I'm not involved in noise reduction for railways, so I don't know exactly what they use, but the basic principles of sound absorption and reflection treatment are basically these. The remaining part is about how the material design specifically eliminates the energy of sound waves.

Comparison between polyester sound-absorbing panels and wooden sound-absorbing panels:  The polyester sound-absorbing board weighs only 5 kilograms per square meter. It is superior in weight to the wooden sound-absorbing board. This makes the building lighter and the construction process simpler.  Sound absorption performance: The polyester sound-absorbing board has a high-frequency absorption rate of 0.99, while the wooden sound-absorbing board has a high-frequency absorption rate of 0.90.  Fire resistance performance: Polyester sound-absorbing panels are divided into national standard B1 flame-retardant panels and fully flame-retardant panels. Wooden sound-absorbing panels only have the national standard B1 fire resistance performance.  Price comparison: The price of the fully flame-retardant polyester sound-absorbing board is 93 yuan per square meter. While the price of the flame-retardant wooden sound-absorbing board that meets national standard B1 requirements is over 120 yuan.  Environmental comparison: Polyester sound-absorbing panels are made by pressing polyester fibers that are directly accessible to the human body. Whether it is direct human contact or the amount of formaldehyde released, they are far more environmentally friendly than traditional wooden sound-absorbing panels.  Construction comparison: Due to the lightweight nature of the polyester sound-absorbing board, the construction process is particularly convenient. After the wall is leveled, simply apply the hot-melt adhesive and stick it directly onto the wall. Because of the 5-kilogram per square meter advantage of the polyester sound-absorbing board, the adhesive can withstand less pressure. It is highly favored by various decoration companies.  Appearance comparison: The polyester sound-absorbing board, due to its diverse color options, can be used in combination with various colors, resulting in excellent aesthetic performance. In contrast, the monotonous color of the wooden sound-absorbing board makes its decorative quality extremely poor.  Touch sensation comparison: The polyester sound-absorbing board has a hardness level between soft panels and wooden perforated boards. It feels moderately soft and hard, making the room more cozy and grand.  The above is a comparison between polyester sound-absorbing panels and wooden sound-absorbing panels. We hope that all buyers can make their own judgments. thank you

National People's Congress representative and professor of the School of Resources and Environmental Sciences at East China Normal University, Chen Zhenlou, believes that plastic-wood composite materials are an environmentally friendly material specifically designed to "digest" waste wood and plastic. Although China is currently a major producer of plastic-wood products, there are issues such as backward technology, scattered production capacity, and lagging national standards that need to be addressed urgently. Chen Zhenlou said that China recycles over 2.5 million tons of waste plastic each year, and cities generate over 8 million tons of wood waste from construction and decoration each year. Wood harvesting and wood processing produce over 100 million tons of branches, fragments, and other waste. Rural areas generate approximately 200 million tons of straw and 35 million tons of rice husks each year. All of these "waste materials" are excellent raw materials for plastic-wood. At the same time, for every 1 ton of plastic-wood composite materials produced, it is equivalent to saving the felling of 1.5 trees that are 30 years old, reducing the pollution caused by 60,000 discarded plastic bags, and eliminating the potential hazards of 114 acres of farmland's plastic film residue. However, there are still many problems in the development of plastic-wood industry in China. The most prominent issue is the lack of product technology research and development, weak and scattered production enterprises, lagging national standards, single product types, high production costs, low added value, and low market acceptance. Chen Zhenlou suggested that the state should regard the plastic-wood industry as a key environmentally supportive industry and provide policy preferences and benefits in areas such as research and development investment, administrative approval, loan financing, sales and production taxes, product promotion and application, government procurement, etc. At the same time, it is necessary to strengthen the research and development of plastic-wood products, support enterprises in independent innovation, and cultivate and support key enterprises. A unified national standard for the plastic-wood industry should be formulated to promote the development of the plastic-wood industry towards the direction of generalization of raw materials, specialization of equipment, and high-end products.

Wavelength The distance that a sound wave travels in one vibration cycle can be calculated by dividing the speed of the sound wave by its frequency. This gives the wavelength of the sound wave. The wavelength range is from 17 meters to 1.7 centimeters. In indoor acoustics, the calculation of the wavelength is of great significance for the analysis of the sound field. The role of the wavelength should be fully emphasized. For example, only when an obstacle has a size larger than one wavelength of the sound wave, will the sound wave reflect normally. Otherwise, phenomena such as diffraction and scattering will intensify, and the shadow area will become smaller, and the acoustic characteristics will be completely different. Another example is that a sound field larger than twice the wavelength is called the far field, and a sound field smaller than twice the wavelength is called the near field. The distribution and propagation laws of the sound field in the far field and near field are very different. Moreover, in smaller-sized rooms (compared to the wavelength), low-frequency sounds cannot be well reproduced because of their longer wavelengths. Therefore, in general households, if the volume of the listening room is not large enough, the low-frequency effect is difficult to reach the ideal state. Many live sound engineers have not taken into account the relationship between audio and wavelength. In fact, this is very important: Audio and wavelength are directly related to the speed of sound. Under the pressure of the air at an altitude and at a temperature of 21 degrees Celsius, the speed of sound is 344 m/s, while the sound speed that I have come into contact with among domestic sound engineers is 340 m/s. This is the speed of sound at a temperature of 15 degrees Celsius, but most people mainly remember that the speed of sound changes with air temperature and air pressure. The lower the temperature, the higher the density of the molecules in the air, so the speed of sound will decrease. And if the live sound is done at a high altitude where the air pressure is reduced, the molecules in the air become more spread out, and the speed of sound will increase. The relationship between audio and wavelength and sound is: wavelength = speed of sound / frequency; λ = v / f. If we assume the speed of sound is 344 m/s, the wavelength of 100 Hz audio is 3.44 m, the wavelength of 1000 Hz (i.e., 1 kHz) is 34.4 cm, and the wavelength of a 20 kHz audio is 1.7 cm. Dynamic range The difference between the maximum and minimum sound pressure levels of audio equipment. The maximum sound pressure level of the equipment is limited by factors such as signal distortion, overheating or damage, so it is the maximum distortion-free sound that the system can produce. The lower limit of the sound pressure level depends on background conditions such as environmental noise, thermal noise, and electrical noise, so it is the smallest sound that can be heard. The larger the dynamic range, the less overload distortion will occur in strong sound signals, so it can ensure that strong sounds have sufficient impact, and can be more realistic when expressing sounds with large and intense changes such as thunder and lightning. At the same time, weak signal sounds will not be drowned out by various noises, and the delicate details will be expressed more vividly. Generally, the dynamic range of a high-fidelity audio system should be greater than 90 decibels. If it is too small, the reproduction of the musical force effect is poor, and the appeal is insufficient. In the adjustment process of professional audio systems, sound engineers should pay attention to the following two issues when adjusting the sound: First, the input gain of the mixer should not be set too low, otherwise weak sounds will be drowned out by the noise of the mixer equipment. Second, the threshold and compression ratio of the limiter should be adjusted with great caution. A too small threshold and a too large compression ratio will cause severe sound dynamic compression, so it should be reduced the dynamic loss of the sound as much as possible while ensuring the effect. In addition, there is also a dynamic range in amplification circuits and audio sources. At this time, the difference between the smallest distinguishable signal and the maximum distortion-free signal can be resolved. Inversion The situation where two identical sound signals have a phase difference of 180 degrees. When the same sound is initiated, the vibration directions of the speaker or microphone between them are opposite, which also belongs to inversion. There are four types of phase inversion in the audio system: left and right channel phase inversion, true phase inversion (i.e., the phase between the input signal and the output signal), microphone phase inversion, and phase inversion of some speakers in an array of multiple speakers. Phase inversion can cause phenomena such as sound short circuit (where the sounds cancel each other out and the volume decreases), loss of sound positioning, and muddy bass, which can cause damage to the reproduction of sound. Decibel A unit of measurement for electrical power gain and sound intensity, named after one-tenth of the unit bel. For every doubling of power, the gain is 3 decibels, and for every increase of 10 times, the gain is 10 decibels. Hass Effect An effect of a dual-source system. When the delay time of one of the two sound sources is within 5 to 35 milliseconds, the listener perceives the sound as coming from the first-arriving source, while the other source seems to not exist. If the delay is from 5 to 50 milliseconds, the sound gradually shifts towards the first-arriving speaker; if the delay is from 30 to 50 milliseconds, one can sense the existence of a lagging sound source. The Haier loudspeaker, named after Dr. Haier of the United States, is a speaker with a folded diaphragm. It was introduced in 1973 and has a special structure of an electric speaker, mainly used for high frequencies. Lauras Effect A pseudo (false) stereo effect. By delaying the signal and superimposing it in reverse on the direct sound signal, a clear spatial impression is immediately produced, and the sound seems to come from all directions. The listener has the feeling of being in the band. Intermodulation Distortion A type of signal distortion where a single audio signal with amplitudes in a certain ratio (usually 4:1) is mixed and through the playback equipment generates new frequency components. It is a nonlinear distortion and the new frequency components include the harmonics of the two single audio signals and various combinations of overtones and undertones.