Sound Transmission Class (STC) is a single-number rating used to describe the airborne sound insulation of building assemblies, including walls, doors, windows, and floor-ceiling systems. This video introduces STC through an everyday concern: hearing conversations from an adjacent room.

Herwin Gunawan explains how STC ratings help designers and building owners compare sound insulation performance and consider speech privacy. The video introduces how ratings are tested and calculated, the differences between lower- and higher-rated assemblies, and the importance of installation quality.

The discussion also highlights why material selection must be considered alongside construction details. Gaps, junctions, and other sound transmission paths can affect the performance experienced in a completed building.

For architects, interior designers, developers, homeowners, and facility teams, the video offers an accessible starting point for making informed decisions about acoustic separation in residential, hospitality, workplace, and other building projects.

Part of the Herwin Gunawan Work video library, this entry reflects ALTA Integra’s evidence-led approach to acoustic design, connecting technical performance with privacy, comfort, and user experience.

Topics: Sound Transmission Class, STC rating, wall sound insulation, airborne sound transmission, speech privacy, building acoustics, acoustic design, ALTA Integra, Herwin Gunawan.