Sound Transmission Loss
Sound Transmission Class (STC)
Outdoor-Indoor Transmission Class
Sound Absorption Testing

Sound Transmission Loss is the amount of sound reduction that occurs in transmission through a partition (door, window, space dividing element, wall assembly, etc.). The sound transmission loss in decibels is typically measured between 80-4000 Hertz frequencies.

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Sound Transmission Class (STC) is a single-number rating, which represents the acoustical performance of a product exposed to an office noise environment. The test evaluates a product's ability to block common interior noises such as speech, radio, and television. The frequency range for this test is 125-4000 Hz (1/3 Octave Bands).

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Outdoor-Indoor Transmission Class (OITC) is a single-number rating, which represents the acoustical performance of a product exposed to an exterior noise environment. The test evaluates a product's ability to reduce air and ground transportation noises such as aircraft, freeway, and railroad. The frequency range for this test is 80-4000 Hz (1/3 Octave Bands).

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Sound Absorption is the amount of sound energy absorbed by an object (office screen, acoustical panel, etc.). Two absorption ratings are generated from the test, which include the Sound Absorption Average (SAA) and Noise Reduction Coefficient (NRC). The Sound Absorption Average is a single-number rating, which represents the average sound absorption coefficient of a product between 200-2500 Hz (1/3 Octave Bands). The Noise Reduction Coefficient is also a single-number rating, which represents the average sound absorption coefficient for 250, 500, 1000, and 2000 Hz frequencies.

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