An alternative for intensity measurement at low frequency in small reverberant rooms

Elisabeth Duarte , Andy Moorhouse , Elvira Viveiros

Intensity measurement is generally used as a reference method, as it is more accurate then measuring sound pressure levels. However, the conventional two- microphone method only provides good accuracy in acoustically dead room. In this paper, a novel method employing an accelerometer and a microphone was used in order to obtain sound intensity close to a wall in reactive field. The tests were done in a reverberant room, whose conditions are not ideal for normal intensity method because the difference between the two microphone signals is swamped by the reverberant component, which gives a large, in-phase sound pressure. Two different intensity methods were used: the conventional two-microphone method and the microphone-accelerometer method. Firstly, the validation method was tested in a semi anechoic room. Subsequently, the same measurement was repeated in a reverberation room with absorption covering one wall and, finally, the same set up was tested in a reverberation room with no absorption whatsoever. There were found good results in low frequencies in all tests but especially in a reverberant room, which showed differences of around 2 to 4 dB between the two methods.

Mots clés: intensity measurement; low frequency; building acoustics

Domaines: Acoustique [physics.class-ph]

Elisabeth Duarte, Andy Moorhouse, Elvira Viveiros. An alternative for intensity measurement at low frequency in small reverberant rooms. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810822⟩