Weighted sound absorption coefficient (αw)

Calculated in accordance with ISO 11654 using the sound absorption coefficient α_p values at standard frequencies and comparing them with a reference curve. The practical sound absorption coefficient α_p is the average of the three 1/3 octave αs values centred on the octave band frequency and rounded in steps of 0.05. The reference curve is shifted downwards in increments of 0.05. This shifts the reference curve to the point where the sum of the negative deviations from the measured values ≤ 0.10 in relation to the values of the reference curve. If this is the case, then the value of 500 Hz on the reference curve is the α_w value. α_w is communicated by all suspended ceiling suppliers in Europe as it is the method which has been adopted as the norm for CE marking of suspended ceilings.