Sound absorption principle
Fiber porous sound absorbing materials, such as centrifugal glass wool, rock wool, mineral wool, plant fiber spraying, etc., the sound absorption mechanism is that there are a large number of tiny connected pores inside the material, along which the sound waves can penetrate into the material and rub against the material. The function converts sound energy into heat. The sound absorbing property of the porous sound absorbing material is that the sound absorption coefficient gradually increases as the frequency increases, which means that the low frequency absorption has no high frequency absorption. The necessary condition for sound absorption of porous materials is : The material has a large number of voids, and the voids communicate with each other, and the pores penetrate deep into the material. One of the misconceptions is that a material with a rough surface has sound absorbing properties, but it is not. For example, the brushed cement and the surface of the stone have no sound absorbing ability. The second misunderstanding is that materials with a large number of holes inside the material, such as polyphenylene, polyethylene, closed-cell polyurethane, etc., have good sound absorption properties. In fact, these materials cannot penetrate due to the lack of connectivity of internal pores. The internal vibration of the material is frictional, so the sound absorption coefficient is small. Â
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A perforated plate with an air layer on the wall or ceiling, even if the material itself has poor sound absorption properties, this structure also has sound absorbing properties, such as perforated gypsum board, wood board, metal plate, and even slit sound absorbing brick. This type of sound absorption is called Helmholtz resonance sound absorption. The sound absorption principle is similar to the acoustic resonance of a thermos bottle. The external space of the material is connected to the internal cavity through a narrow bottleneck. When the sound wave is incident, at the resonance frequency, the neck is The intense resonance between the air and the internal space consumes acoustic energy. The Helmholtz resonance absorption is characterized by a large sound absorption coefficient only at the resonance frequency. Â
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The film or sheet can also absorb sound when there is a cavity in the wall or ceiling, such as a ceiling made of wood board or metal sheet or wall panel. The sound absorption mechanism of this structure is thin sheet resonance sound absorption. At the resonance frequency, a large amount of acoustic energy is absorbed due to the severe vibration of the thin plate. Thin plate resonance absorption mostly has good sound absorption performance at low frequencies.
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Explain the principle of sound absorption in general:
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The principle of sound absorption is to leave a channel for the sound to enter (a channel composed of numerous tiny holes that are connected together, or a mixture of countless fibers intertwined to form numerous small gaps) but the sound comes in once it enters No, because the passage is too long, the sound is drilled in and out, and the left and right collision In this process, energy is gradually consumed and plays a role in sound absorption.
Fiber porous sound absorbing materials, such as centrifugal glass wool, rock wool, mineral wool, plant fiber spraying, etc., the sound absorption mechanism is that there are a large number of tiny connected pores inside the material, along which the sound waves can penetrate into the material and rub against the material. The function converts sound energy into heat. The sound absorbing property of the porous sound absorbing material is that the sound absorption coefficient gradually increases as the frequency increases, which means that the low frequency absorption has no high frequency absorption. The necessary condition for sound absorption of porous materials is : The material has a large number of voids, and the voids communicate with each other, and the pores penetrate deep into the material. One of the misconceptions is that a material with a rough surface has sound absorbing properties, but it is not. For example, the brushed cement and the surface of the stone have no sound absorbing ability. The second misunderstanding is that materials with a large number of holes inside the material, such as polyphenylene, polyethylene, closed-cell polyurethane, etc., have good sound absorption properties. In fact, these materials cannot penetrate due to the lack of connectivity of internal pores. The internal vibration of the material is frictional, so the sound absorption coefficient is small. Â
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A perforated plate with an air layer on the wall or ceiling, even if the material itself has poor sound absorption properties, this structure also has sound absorbing properties, such as perforated gypsum board, wood board, metal plate, and even slit sound absorbing brick. This type of sound absorption is called Helmholtz resonance sound absorption. The sound absorption principle is similar to the acoustic resonance of a thermos bottle. The external space of the material is connected to the internal cavity through a narrow bottleneck. When the sound wave is incident, at the resonance frequency, the neck is The intense resonance between the air and the internal space consumes acoustic energy. The Helmholtz resonance absorption is characterized by a large sound absorption coefficient only at the resonance frequency. Â
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The film or sheet can also absorb sound when there is a cavity in the wall or ceiling, such as a ceiling made of wood board or metal sheet or wall panel. The sound absorption mechanism of this structure is thin sheet resonance sound absorption. At the resonance frequency, a large amount of acoustic energy is absorbed due to the severe vibration of the thin plate. Thin plate resonance absorption mostly has good sound absorption performance at low frequencies.
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Explain the principle of sound absorption in general:
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The principle of sound absorption is to leave a channel for the sound to enter (a channel composed of numerous tiny holes that are connected together, or a mixture of countless fibers intertwined to form numerous small gaps) but the sound comes in once it enters No, because the passage is too long, the sound is drilled in and out, and the left and right collision In this process, energy is gradually consumed and plays a role in sound absorption.
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