The Importance of Acoustic Performance in Building and Construction

When examining the acoustic performance of a building, there are several factors to consider, including Sound Transmission Class (STC) and Outdoor-Indoor Transmission Class (OITC) of products used on the building. STC and OITC have become increasingly important measurements for architects and building designers to understand when determining sound insulation needs. 

STC and OITC ratings reflect the magnitude of sound transmission being blocked by a barrier, such as a wall, door or window. The higher the STC or OITC value, the lower the magnitude of sound transmission through the barrier. In this article, we will define STC and OITC in building and construction, the importance of these rating systems and how these measurements demonstrate the acoustic performance of a facade.  

What is Sound Transmission Class (STC)? 

Sound Transmission Class (STC) has been around for many years and represents how well a barrier blocks airborne sound and noise between interior rooms. The higher the STC rating, the better the material prevents sound from passing through interior spaces. STC rates sound transmission over a frequency range (from 125 to 4000 hertz) and is applicable to mid- to high-frequency noises, such as conversations, music, television and more. These ratings are vital in buildings where noise control is critical, including multifamily buildings, office spaces, schools and hospitals. 

What is Outdoor-Indoor Transmission Class (OITC)? 

In recent years, Outdoor-Indoor Transmission Class (OITC) has gained popularity when examining the exterior acoustic performance of a building. OITC applies to the noise that passes from the outside of a building to the inside of a building. The OITC rating system measures the transmission of low-frequency noises (80 to 4000 hertz) —highway traffic, car horns, machinery, construction and low-flying airplanes—through exterior walls, windows, doors and other facade elements into a building’s interior. This rating system also allows architects and glaziers to determine what building materials to use for their project based on a building’s location and the importance of sound reduction in the facade. These ratings are important in buildings where external noises tend to be more frequent such as in urban areas. 

STC and OITC Testing for Architectural Aluminum Systems 

Validating the acoustic performance of our products and systems is a priority. At Kawneer, we continue to innovate and are committed to providing quality products that meet project needs for acoustic performance. Kawneer provides a variety of architectural aluminum systems with acoustic performance, complete with STC and OITC ratings, from storefront framing and entrances to windows, curtain wall and window wall systems.  

Our products have been tested for acoustic performance according to American Architectural Manufacturers Association (AAMA) 1801 and American Society for Testing and Materials (ASTM) E90. The STC and OITC ratings have been calculated according to ASTM E413 and ASTM E1332. Our products have been tested to help contribute to quieter indoor environments—ideal for living, working and relaxing—regardless of exterior noise. 

STC and OITC values are now available for a wide range of Kawneer products. Read our acoustic performance whitepaper to learn more.

Visit our Acoustic Performance webpage to learn more about how acoustic performance is an increasing priority for modern architectural design and is becoming a recurring requirement in project specifications.