Sound Amplification Block Made of Air-Permeable Material and Air-Absorbing Material and Having Layered Structure, and Manufacturing Method Thereof

A method of manufacturing a sound amplifying block having a layered structure, the method comprising:

• a first operation of preparing a slurry by mixing a first porous material, which is an air adsorbing material that serves to amplify sound, a second porous material, which is a permeable material and has a larger pore size and porosity than those of the first porous material, a binder, a solvent, and an additive;
• a second operation of injecting the slurry into a mold, bringing the mold containing the slurry into contact with a freezing plate maintained at a temperature below a freezing point of the slurry, growing grains in a direction of a temperature gradient, and freeze-casting the grains to form a layered structure, and
• a third operation of sublimating water, while freeze-drying the freeze-cast block, to form a structural gap.