Sound is transmitted through most walls and floors by setting the entire structure into vibration. This vibration generates new sound waves of reduced intensity on the other side. The passage of sound into one room of a building from a source located in another room or outside the building is termed ''sound transmission".
Thermal insulation is the reduction of heat transfer (the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials
The refractory lining is a protective layer installed inside the kiln or furnace to insulate the furnace steel structure from high temperatures. It also protects it from thermal shocks and chemical attack, and abrasion wears. It may consist of refractory bricks or monolithic refractories such as castable, gunning mixes. The refractory selection depends upon the temperature inside the unit and the chemical nature of the material being processed. The thickness of the lining is generally in the range 80 to 300mm. The shell must be maintained at low temperature to avoid deformation and also to save energy and protect the plant personnel.