Page 224 - The Master Handbook Of Acoustics

199
ABSORPTION OF SOUND

affecting the absorption of carpets and make judgments on what coef-
ficients to use for the specific carpet at hand.

Effect of Carpet Type on Absorbance
What variation in sound absorption should one expect between types
of carpet? Figure 9-17 shows the difference between a heavy Wilton
carpet and a velvet carpet with and without a latex back. The latex
backing seems to increase absorption materially above 500 Hz and to
decrease it a modest amount below 500 Hz.

1.0

B

0.8

A
Absorption coefficient 0.4 C
0.6

0.2

0
125 250 500 1 kHz 2 kHz 4 kHz
Frequency - Hz
FIGURE 9-17
A comparison of the sound-absorption characteristics of three different types of carpet.
(A) Wilton, pile height 0.29″, 92.6 oz/sq yd. (B) Velvet, latex backed, pile height
0.25″, 76.2 oz/sq yd. (C) The same velvet without latex backing, 37.3 oz/sq yd, all with
5
40-oz hair felt underlay. (After Harris. )