In the family of sound-absorbing materials, in order to meet the different needs of building functions, in addition to the resonance sound-absorbing structure, there is also a special sound-absorbing material based on porous sound-absorbing materials and composed in a certain way, which has a wide absorption frequency band and absorbs a large amount of sound energy, which can meet people's requirements for sound-absorbing effect. This kind of special sound-absorbing materials mainly include: curtains, space sound-absorbing bodies and sound-absorbing sharp splits.
Curtain. The curtain is a textile with breathing properties, with the sound absorption characteristics of porous materials, because it is thinner and it is used as a sound absorbing material to get a large sound absorption effect. If it is used as a curtain and installed at a certain distance away from the wall or window opening, just like the air layer is set behind the porous material, it can have a certain sound absorption effect at medium and high frequencies. When it is hung at odd times of the wavelength of the wall 1 4, a high amount of sound absorption of the corresponding frequency can be obtained.
Space sound absorbers.
A sound-absorbing component that is dispersed and suspended in the upper part of the building space to reduce indoor noise or improve indoor sound quality. The space sound absorber has the characteristics of less materials, light weight, low investment, high sound absorption efficiency, flexible layout and convenient construction.
According to the use nature, area, floor height, structural form, decoration requirements and sound source characteristics of the building, the space sound absorber can have a variety of shapes such as plate, square, column, conical and spherical; Make it absorb sound waves in multiple faces, in the case of the same projection area, it is equivalent to increasing the effective sound absorption area and edge effect, so that the sound wave is reflected many times between the upper top surface of the sound absorbing body and the top surface of the building, so that it is absorbed many times, and the sound absorption volume increases, coupled with the diffraction of sound waves, greatly improves the actual sound absorption effect, usually the improvement of sound absorption efficiency in the medium and high frequency bands is the most significant, and its high-frequency sound absorption coefficient can reach 140。Among them, the plate-like structure is the simplest and the most widely used. Space sound absorbers are mostly used in indoor gymnasiums, and their various shapes and furnishings can enhance the decorative effect of the interior, and the most important thing is its sound absorption performance, which can prevent echo defects in large halls and effectively reduce reverberation time. In actual use, according to different places and requirements, various forms of sound absorbers can be designed to hang down from the ceiling. It is widely used in indoor gymnasiums, factories with excessive noise, and is also suitable for radio stations, television recording studios, studios, schools, grand theaters, libraries, cultural centers, auditoriums, multi-function halls, conference rooms and halls and other places with high requirements for sound quality.
Spatial sound absorbers are generally scattered and suspended in the sound field below the ceiling of a room or hall, and the common space sound absorbers are composed of a skeleton, a protective layer and a sound-absorbing filler. The choice of materials should be determined by the size, stiffness and decoration requirements of the space absorber; Appropriate geometries and dimensions are made according to the use occasion and sound absorption needs.
Components: Skeleton: As a support, it can be used as wood bars, angle steel or thin-walled steel, etc.
Protective layer: the commonly used perforation rate is greater than 20%, and the thickness is 01-1.0mm perforated or seamed thin iron sheet, aluminum foil or plastic sheet, perforated hole diameter of 4-8mm.
Sound-absorbing filler: generally use porous materials such as ultra-fine glass wool felt, mineral wool felt, asphalt glass wool felt, etc., and use glass fiber cloth and other materials with good air permeability and certain strength as the masking layer. In humid environments, single- or double-layer perforated panels can also be used as sound-absorbing layers to replace porous materials.
Hanging parts: such as metal lifting lugs, hooks, bolts, etc. When used, each surface is placed in the sound field, which is conducive to giving full play to the sound absorption effect of the material.
Most of the space sound absorbers have good sound absorption performance, sound absorption frequency bandwidth, effective control and adjustment of indoor reverberation, fire prevention, moisture-proof, simple installation, beautiful appearance, flexible and convenient assembly. There are various shapes and specifications, and the common ones are as follows.
Triangular space sound absorber
Box space sound absorber.
Box space sound absorber.
Mushroom-shaped space absorber.
Other spatial sound absorbers.
Sound-absorbing spikes. Acoustic spike splitting is a special sound-absorbing structure used in anechoic chambers. It is composed of two parts: the sharp split and the base that connects and fixes the sharp split. Sound absorption snig splitting is the use of special impedance of the gradual change, from the characteristic impedance of the end face of the sharp split, close to the characteristic impedance of air, and gradually transition to close to the characteristic impedance of sound absorbing materials, so as to achieve the highest sound absorption effect, and its average sound absorption coefficient can reach 10。There is no fixed value for the length of the sharp split, the longer the better, the sharp split low frequency sound absorption performance is good, and its cut-off frequency is about 688～86hz。The width is generally 03～0.4m with a base thickness of 01m。Generally, 3 sharp splits and the base form a unit, and multiple units can be used according to the site design requirements. The sound-absorbing sharp split is generally hung on the roof or four walls, and there should be a certain space behind it and the wall, about 005～0.1m, in order to form a layer of air, improve sound absorption. When the thickness of the air layer is 1 4 wavelengths, the sound absorption coefficient is maximum. At the same time, the incident sound wave can penetrate the sound-absorbing spike or diffract it through the surrounding area to the back of the spike, and the spike can absorb sound many times through refraction and reflection with the roof. The main factors influencing the sound absorption at low frequencies are the base of the cleave and the air layer. In practical applications, there are flat top type, straight strip type and layered stepped type and other sharp splits.
Anechoic chamber. This kind of special sound-absorbing material has a significant sound-absorbing effect, not only the shape is varied, but also the sound-absorbing surface has a variety of colors to choose from, the application of this kind of material, under the premise of achieving high standard sound-absorbing performance, can be based on the shape of the material used, use the appropriate color, arrange a pleasing modeling pattern. To meet people's great needs for hearing and vision, it is the best choice for building decoration with excessive noise and high sound quality requirements!