Absorption coefficient - Ratio of sound absorbing effectiveness, at a specific frequency, of a unit area of acoustical absorbent to a unit area of perfectly absorptive material. The portion of energy absorbed when a sound wave strikes a material. The absorption coefficient of a material is dependent on the frequency of the sound wave. An absorption coefficient of 1.0 = total absorption, 0.0 = total reflection. Note: See Area Effect for explanation of absorption coefficients exceeding 1.00.