There are three main strategies to reduce noise in interior architecture: sound insulation, sound absorption, and sound masking. Sound insulation is the process of preventing or minimizing the transmission of noise from one space to another, or from outside to inside. Sound insulation can be achieved by using materials that have high mass, density, and stiffness, such as concrete, brick, or metal, or by creating air gaps or cavities between walls, floors, or ceilings. Sound absorption is the process of reducing the reflection and reverberation of noise within a space, making it quieter and more comfortable. Sound absorption can be achieved by using materials that have low density, porosity, and elasticity, such as fabric, foam, or wood, or by adding acoustic panels, tiles, or curtains. Sound masking is the process of adding a background noise that covers or reduces the perception of unwanted noise, such as white noise, pink noise, or nature sounds. Sound masking can be achieved by using devices that generate or play these sounds, such as speakers, fans, or fountains.