Sound Transmission Class is an integer rating of how well a building partition attenuates airborne sound. In the US, it is widely used to rate interior partitions, ceilings, floors, doors, windows and exterior wall configurations. Outside the US, the ISO Sound Reduction Index (SRI) is used. The STC rating very roughly reflects the decibel reduction of noise that a partition can provide. The STC is useful for evaluating annoyance due to speech sounds, but not music or machinery noise as these sources contain more low frequency energy than speech.
Sound Transmission Class Report Sample from NTi Audio showing Transmission Loss in the sixteen standard frequencies
A small gap in the wall can greatly reduce the STC rating. This wall did not receive a full perimeter seal.
Architectural acoustics is the science and engineering of achieving a good sound within a building and is a branch of acoustical engineering. The first application of modern scientific methods to architectural acoustics was carried out by the American physicist Wallace Sabine in the Fogg Museum lecture room. He applied his newfound knowledge to the design of Symphony Hall, Boston.
Symphony Hall, Birmingham, an example of the application of architectural acoustics
Ceiling of Culture Palace (Tel Aviv) concert hall is covered with perforated metal panels
An anechoic chamber, using acoustic absorption to create a dead space.
