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(STC) Sound Transmission & (IIC) Impact Isolation

A diagram shows sound waves traveling toward a vertical barrier, with reduced size as they pass through—illustrating Sound Transmission Class (STC)—and finally reaching an ear on the right side of the image.

Sound Transmission Class (STC) and Impact Isolation Class (IIC) are crucial metrics in architectural design, quantifying a barrier's ability to reduce airborne and impact noise, respectively. Understanding these values is essential for creating acoustically sensitive environments, from music venues to multi-family residences. This guide explores the nuances of STC and IIC, offering best practices for controlling sound transmission and impact isolation to enhance user experience and meet code requirements.