A diffuser is a device that disperses or expands the sound waves emitted by an instrument, in order to create the most even possible audible texture. The placement of the diffusers will depend on the size and shape of the room, but usually they are placed behind the instrumentalist, in line with their head.
High levels of indoor humidity can be uncomfortable or even unhealthy. Humidifiers are designed to maintain an indoor humidity level of 30-60%. A humidifier typically increases the humidity in a room by evaporating water into the air.
Air purifiers use a filter to trap and remove pollutants and particles from the air. Different types of particles can be removed, such as allergens, bacteria, and dust.