Civil Engineering Reference
In-Depth Information
incidence plane wave having a sound pressure of 1 Pa. We observe that the displacement
has a pronounced maximum in the same frequency range as found for the absorption
curve.
1.0
0.9
0.8
0.7
0.6
0.5
0.4
Measured (L1)
Measured (L2)
FEM
Analytical
0.3
0.2
0.1
0.0
0
500
1000
1500
2000
2500
3000
Frequency (Hz)
Figure 5.30
Normal incidence
absorption factor of 50 mm polyurethane with hard backing. Measurement data,
using a two-microphone free field technique and two loudspeaker positions (L1, L2), are compared both with
analytical results and results using a finite element method (FEM). From Vigran et al. (1997).
2.0E-004
1.5E-004
1.0E-004
5.0E-005
0.0E+000
0
500
1000
1500
2000
2500
3000
Frequency (Hz)
Figure 5.31
Calculated displacement at the surface of 50 mm thick polyurethane foam. Incident sound pressure
equal 1 Pa.
