It is a measure of how much sound will be prevented from being transferred from one area to another. The higher the rating, the less sound can be heard on the other side. This is a logarithmic progression, as opposed to a linear variable. Various STC Value ranges and their descriptions are listed above. Generally, the performance of sound control doors is based in large part on the mass of the door.
Sound doors are heavier than conventional hollow metal doors.
Also, the door frame is made of thicker materials than those used to hang a conventional hollow metal door, which weighs seven to eight pounds per square foot. In colleges, these doors can be found in music practice rooms, radio or TV broadcast stations, mechanical equipment rooms and conference rooms. Galvanized doors and frames are used in exterior applications to prevent rust, especially in areas where there is spray from salt water. They are also found in waste water treatment plants and other areas with chemicals in use, such as chemistry buildings. There are four major groups of stainless steel.