Page 268 - Master Handbook of Acoustics

chamber measurements of absorption coefficients for a single Axminster type of carpet with different
2
underlay conditions. Graphs A and C show the effect of hair felt of 80 and 40 oz/yd weight. Graph B
shows an intermediate combination of hair felt and foam. While these three graphs differ

considerably, they all stand in contrast to graph D for the carpet laid directly on bare concrete. We
conclude that the padding underneath the carpet contributes markedly to overall carpet absorption.

FIGURE 12-20 Sound-absorption characteristics of the same Axminster carpet with different

underlay. (A) 80-oz hair felt. (B) Hair felt and foam. (C) 40-oz hair felt. (D) No underlay, on bare
concrete. (Harris.)

Carpet Absorption Coefficients

The absorption coefficients plotted in Figs. 12-19 and 12-20 are taken from a study of carpet