Structure having sound absorption characteristic
To absorb a noise produced by an external force that generates an audio frequency even if it is applied thereto, and to make it hard to become a noise source to a surrounding area. It includes a surface layer 20 having microscopic pores 21 formed on a surface 20 A, communicating passages 24 communicating with the microscopic pores 21 and a porous layer 10 having sound pores 14 that are formed at an inner part deeper than the surface layer 20 having the microscopic pores 21 formed, communicate with the communicating passage 24 and that have a volume larger than volumes of the microscopic pore 21 formed on the surface 20 A and the communicating passage 24 . A sound absorption characteristic and/or a sound insulation characteristic is provided by the microscopic pores 21 of the surface 20 A, the communicating passages 24 of the porous layer 10 , and the sound pores 14 of the porous layer 10 . Accordingly, sound absorption control including sound insulation in a predetermined audio frequency band can be achieved and a high sound absorption characteristic can be provided.
1. A structure having a sound absorption characteristic comprising:
a surface layer having microscopic pores formed on a part of a surface,
communicating passages communicating with the microscopic pores, and
sound pores of a porous layer that are formed at an inner part deeper than the surface layer and that have a volume larger than volumes of the microscopic pore and the communicating passage,
wherein the surface layer, the communicating passages, and the sound pores are provided on a portion where at least one of a sound absorption characteristic and a sound insulation characteristic that is desired,
wherein a part of the sound pores communicates with the microscopic pore through the communicating passage, while another part of the sound pores forms closed spaces by being connected to the surface layer, and
wherein the structure is formed by coating and foaming a foamable synthetic resin composition, which provides at least one of the sound absorption characteristic and/or the sound insulation characteristic by the microscopic pores of the surface layer, the communicating passages, the sound pores, and the surface layer which is in contact with the sound pores, on the portion where at least one of the sound absorption characteristic and the sound insulation characteristic is desired.
2. A structure having a sound absorption characteristic according to claim 1 , wherein at least one of the sound absorption characteristic and the sound insulation characteristic provided by the microscopic pores of the surface layer, the communicating passages, the sound pores and the surface layer that contact the sound pores is such that the microscopic pores have an area ratio of pores to the surface at 0.1% to 10% to provide a sound absorption characteristic in a frequency band including at least 1000 Hz in an audible frequency range of a human being by a resonance in spaces communicating from the microscopic pores to the sound pores and a film resonance by the surface layer, the microscopic pores thereof and the sound pores.
3. A structure having a sound absorption characteristic according to claim 1 , wherein a density of the surface layer is higher than a density of the porous layer.