Sound Absorptive Tiles is the phenomenon of energy loss after sonic impact to the surface of the material. Sound Absorptive Tiles can reduce the indoor sound pressure level. The index of Sound Absorptive Tiles is the Sound Absorptive Tiles coefficient α, which represents the ratio of the acoustic energy absorbed by the material to the incident energy. Theoretically, if a material completely reflects the sound, then its α = 0; if a material absorbs all the incoming sound energy, then it's α = 1. In fact, all materials α between 0 and 1, that is, can not be all reflected, it is impossible to absorb all.
Different frequency will have different Sound Absorptive Tiles coefficient. People use the Sound Absorptive Tiles coefficient frequency characteristic curve to describe the Sound Absorptive Tiles performance of the material at different frequencies. In accordance with ISO standards and national standards, Sound Absorptive Tiles test report in the absorption coefficient of the frequency range is 100-5KHz. The average Sound Absorptive Tiles coefficient of 100-5KHz Sound Absorptive Tiles coefficient is the average Sound Absorptive Tiles coefficient, the average Sound Absorptive Tiles coefficient reflects the overall Sound Absorptive Tiles performance of the material.
In the project often use the noise reduction coefficient NRC to roughly evaluate the Sound Absorptive Tiles performance in the language frequency range, this value is the material at 250, 500, 1K, 2K four frequency of the Sound Absorptive Tiles coefficient of the arithmetic mean, rounded rounded to 0.05. It is generally believed that materials with NRC less than 0.2 are reflective materials and materials with NRC greater than or equal to 0.2 are considered to be sound absorbing materials. When you need to absorb a lot of sound can reduce the indoor reverberation and noise, often need to use high Sound Absorptive Tiles coefficient of the material. Such as centrifugal glass wool, rock wool and other high-NRC sound-absorbing material, 5cm thick 24kg / m³ of centrifugal glass wool NRC can reach 0.95.
There are two ways to measure the Sound Absorptive Tiles coefficient of a material, one is the reverberation chamber method, one is the standing wave tube method. Reverberation chamber method to measure the sound of random incidence of Sound Absorptive Tiles coefficient, that is, sound from all directions into the material when the energy loss ratio, while the standing wave tube method to measure the sound is incident when the Sound Absorptive Tiles coefficient, the sound angle of only 90 degrees The
The two methods measure the Sound Absorptive Tiles coefficient is different, the most commonly used in the project is the reverberation chamber method to measure the Sound Absorptive Tiles coefficient, because the actual application of the sound input is random. In some measurement reports, there will be a case where the Sound Absorptive Tiles coefficient is greater than 1, which is due to the measurement of laboratory conditions, etc. In theory, the acoustic energy absorbed by any material can not be greater than the incident sound energy, and the Sound Absorptive Tiles coefficient is always less than one. Any measured Sound Absorptive Tiles coefficient greater than 1 in the actual acoustic engineering calculations can not be used by more than 1, up to 1 to calculate.
In the room, the sound will soon fill every corner, so the Sound Absorptive Tiles material placed in the room on any surface have Sound Absorptive Tiles effect. The greater the Sound Absorptive Tiles coefficient of the sound absorbing material, the more Sound Absorptive Tiles area, the more obvious the Sound Absorptive Tiles effect. You can use sound-absorbing ceilings, sound-absorbing wall panels, space sound absorbers, such as Sound Absorptive Tiles noise reduction.
Fiber porous sound-absorbing material, such as centrifugal glass wool, rock wool, mineral wool, plant fiber spraying, Sound Absorptive Tiles mechanism is a large number of tiny pores within the material, the sound along these pores can be deep inside the material, and material friction The role of sound energy into heat. The Sound Absorptive Tiles characteristics of the porous sound-absorbing material are increased with increasing frequency, which means that the low-frequency absorption is not high-frequency absorption.
The necessary conditions for the Sound Absorptive Tiles of porous materials are: the material has a large number of gaps, the gap between each other, the pores into the material inside. One of the misconceptions is that the surface roughness of the material with Sound Absorptive Tiles performance, it is not true, such as pull the cement, the surface of the concave and convex stone is basically no Sound Absorptive Tiles capacity. The second is to understand the material is a large number of holes within the material, such as polystyrene, polyethylene, closed-cell polyurethane, etc., with good Sound Absorptive Tiles performance, in fact, these materials due to internal holes are not connected, Material internal vibration friction, so the Sound Absorptive Tiles coefficient is very small.
With the walls or ceilings exist in the air layer of the perforated plate, even if the material itself Sound Absorptive Tiles is poor, this structure also has Sound Absorptive Tiles performance, such as perforated gypsum board, wood, metal plate, and even slit Sound Absorptive Tiles brick. This type of Sound Absorptive Tiles is called Helmholtz resonance Sound Absorptive Tiles, the Sound Absorptive Tiles principle is similar to the thermosacoustic acoustic resonance, the material external space and the internal cavity through a narrow bottleneck connection, sound wave incident, the resonance frequency, the neck The intense resonance between the air and the internal space consumes sound energy. Helmholtz resonance absorption is characterized by only a large absorption coefficient at the resonant frequency.