Modelling multilayered systems with porous materials using the transfer matrix method - Propagation of Sound in Porous Media - page 272

1.2

1

0.8

0.6

0.4

Test: Felt + Perforated screen + Foam
Test: Foam
Test: Felt
Prediction: Foam
Prediction: Felt
Prediction: Felt + Perforated screen + Foam

0.2

0

200 400 600 800 1000 1200 1400 1600 1800 2000

Frequency (Hz)

Figure 11.13 The absorption coefficient of a felt - screen -foam system; comparison
between measurements and predictions. Measurements reproduced from Atalla and Sgard
(2007). Reprinted from Atalla, N. & Sgard, F. Modelling of perforated plates and screens
using rigid frame porous models. J. Sound Vib. 303 (1 - 2), 195 - 208. (2007) with per-
mission from Elsevier.

qq

M 4

Screen M 3

M 2 X 1

Porous layers

X 3

M 1

Figure 11.14 A porous material surfaced with an impervious screen and bonded on to
a rigid impervious wall.