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- Transmission Loss - the reduction in noise level resulting from passage
through an obstruction at a given frequency. Sound transmission class (STC) is
the overall measurement of the effectiveness of a material to attenuate sound.
Values are expressed in decibels and as such form a logarithmic scale. The
higher the transmission loss, the more effective the material is.
- Acoustic Loss Factor - a measure of the ability to reduce structural borne sound. It represents how much vibration related energy is absorbed by the material at a given temperature. Based on a linear scale of 0 - 1, with 0 being an undamped steel panel and 1 being a theoretically perfectly damped panel (no vibration). The higher the ALF, the more effective the material is. Also known as Damping Loss Factor (DLF)
- Absorption Coefficients - the amount of sound energy a surface absorbs and reflects at a given frequency. If we say that a surface material has an absorption coefficient of 0.25 we are saying that the surface will absorb 25% of the incident acoustic energy, while reflecting back 75% of the total acoustic energy at the specified frequency. The higher the absorption coefficient, the more effective the material is.
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