Building Acoustics

120 Building acoustics 6 and 9 dB higher than the average level in the room. This is also easily demonstrated by direct measurem ...

Room acoustics 121 developed taking account of the fact that the reverberation is not a continuous process but involves a stepwi ...

122 Building acoustics experimental investigation in two different rooms comparing, altogether, seven different formulae. Howeve ...

Room acoustics 123 Figure 4.8 Power attenuation coefficient m for atmospheric absorption at 20° Celsius. Calculated from ISO 961 ...

124 Building acoustics referred in section 4.5.1.1 above to the standard ISO 3741 on sound power determination in a reverberatio ...

Room acoustics 125 (^2) tot 0 0 2 4 . 4 D pWc r A ρ θ π ⎛⎞ =⎜ ⎝⎠  +⎟ (4.48) Expressed by the corresponding levels using standar ...

126 Building acoustics Example In Figure 4.9 we calculated the difference between the sound pressure and the power levels for th ...

Room acoustics 127 The Schroeder cut-off frequency represents an important division in the prediction of the variance. A satisfa ...

128 Building acoustics chooses a measurement time making the time variance some one-tenth of the expected spatial variance. If t ...

Room acoustics 129 63 125 250 500 1000 2000 4000 Frequency (Hz) 0 1 2 3 4 5 6 Standa rd deviation (dB) Volume 102 m^3 Figure 4.1 ...

130 Building acoustics 4.5.2.2 Reverberation time variance Measurements of sound decay and reverberation time in rooms are perfo ...

Room acoustics 131 (^) r^2 () 0 1.94 1.31 T N , fTM σ + = (4.59) where f 0 is the centre frequency in the one-third-octave band. ...

132 Building acoustics analysis; e.g. in a sound power determination in a reverberation room. In other cases, we shall set up a ...

Room acoustics 133 (^) eq^0 0 4 4 (circular path). r rf M c π π λ ≈= (4.62) The quantities r and f 0 are the path radius and the ...

134 Building acoustics source method. The models implemented in software programs are, however, given special names depending on ...

Room acoustics 135 4.6.2 Image-source models Image-source (or mirror-source) modelling is based on regarding all reflections fro ...

136 Building acoustics Source R S 1 W Figure 4.15 Example on image source not being visible in receiver positions R. We shall pu ...

Room acoustics 137 4.6.3 Hybrid models A number of the computer programs for room acoustic predictions are based on models that ...

138 Building acoustics size of objects. The energy in the incident wave will be redistributed with a directional distribution de ...

Room acoustics 139 planes. We shall confine ourselves to the first type, as the extension to two dimensions is reasonably straig ...