What are STC and OITC?

STC (Sound Transmission Class) and OITC (Outdoor-Indoor Transmission Class) are ratings used to measure the soundproofing effectiveness of building materials, particularly windows, doors, and walls.

STC (Sound Transmission Class)

STC is a rating system that measures how well a building partition attenuates airborne sound. It is used to assess the soundproofing effectiveness of interior walls, ceilings, floors, doors, and windows. The higher the STC rating, the better the material is at reducing sound transmission. Key points about STC:

1. Frequency Range: STC ratings typically focus on sounds in the range of 125 Hz to 4000 Hz, which covers most of the frequencies associated with human speech.
2. Application: Commonly used in interior environments where controlling noise between rooms or spaces is important, such as in offices, apartments, and hotels.
3. Measurement: The STC rating is determined by measuring the transmission loss of a material at various frequencies and comparing it to a standard reference curve.

OITC (Outdoor-Indoor Transmission Class)

OITC is a rating system that measures how well a building partition attenuates both airborne sound and low-frequency noise, particularly from outdoor sources such as traffic, aircraft, and other environmental noises. Key points about OITC:

1. Frequency Range: OITC ratings cover a broader range of frequencies (typically from 80 Hz to 4000 Hz) than STC, with more emphasis on lower frequencies that are common in environmental noise.
2. Application: Primarily used to evaluate the soundproofing effectiveness of exterior walls, windows, and doors in buildings exposed to significant outdoor noise, such as those near highways, airports, or industrial areas.
3. Measurement: The OITC rating is determined by measuring the transmission loss of a material across a range of frequencies and comparing it to a specific reference curve that reflects typical outdoor noise spectra.

In summary, while both STC and OITC are used to rate the soundproofing effectiveness of building materials, STC is more suited for indoor noise control, and OITC is designed to evaluate the reduction of outdoor noise entering a building.