Building Acoustics

182 Building acoustics

50 100 200 500 1000 2000 5000

Frequency (Hz)

-10.0

-9.0

-8.0

-7.0

-6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

Normalized impedance

Model

Delany - Bazley

Mechel

Figure 5.18 Real and imaginary part of the input impedance of a 50 mm thick material with a hard backing
(normal incidence). Comparison of models by Delany-Bazley and Mechel.

100 1000

50 200 500 2000 5000

Frequency (Hz)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

A

bso

rption facto

r

Model

Delany - Bazley

Mechel

Figure 5.19 Absorption factor corresponding to the data shown in Figure 5.18.