Building Acoustics

180 Building acoustics the same as the quantity perforation rate ε used in section 5.4.1.5. Here we have to put r = r'/σ and Z = ...

Sound absorbers 181 It is assumed that the quantity E lies inside the range 0.01–1.0. As mentioned above, the model has been and ...

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 ...

Sound absorbers 183 above is that Wilson’s model also repairs the anomaly of the Delany-Bazley model giving a realistic predicti ...

184 Building acoustics 100 1000 200 400 600 800 2000 4000 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 rptio ...

Sound absorbers 185 increased flow resistivity. This is easily demonstrated by Figure 5.21 showing again the absorption factor f ...

186 Building acoustics absorption. Taking porous materials as an example, we find that an angle of incidence 50–60° will give a ...

Sound absorbers 187 where Re again denote the real part of the actual quantity. In Figure 5.23, we have again used a porous mate ...

188 Building acoustics where Zf is denoted field impedance, a quantity that may be interpreted as a radiation impedance for a pl ...

Sound absorbers 189 125 250 500 1000 2000 4000 Frequency (Hz) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 Ab ...

190 Building acoustics 5.5.4.1 The model of Attenborough Attenborough (1983,1992), introduces an additional parameter sf, denote ...

Sound absorbers 191 to calculate Zc and Γ according to Equations (5.60) and (5.61), which in turn enable us to calculate the res ...

192 Building acoustics of material parameters). Concerning the size of these parameters, one will find values in the range of so ...

Sound absorbers 193 When both lengths are relatively large and of equal size the absorption characteristic is similar to the one ...

194 Building acoustics the former, for which the attenuation is large due to the viscous coupling between frame and air, is trad ...

Sound absorbers 195 incidence plane wave having a sound pressure of 1 Pa. We observe that the displacement has a pronounced maxi ...

196 Building acoustics 5.6 Measurements of material parameters In general, there exist several methods for determining the mater ...

Sound absorbers 197 The quantities R, Rs and r are defined by the following (^) s s v ,and P R RRRSr qd Δ ==⋅=. (5.67) The quant ...

198 Building acoustics where μ is the coefficient of viscosity. 5.6.2 Porosity By the porosity of a porous material, it is under ...

Sound absorbers 199 We have then determined the unknown total volume V of air in the chamber, V= V 0 + Vf. Since the volume V 0 ...