Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Precision measuring device of sound intensity

Acoustic FieldAcoustic impedanceComplex Acoustic IntensityPrecision Measuring DeviceSignal Processing


The invention is a device for measuring the complex sound intensity, active and reactive intensity, with 3D spectral resolution in any situation. The new methodology is based in the impedance computation and it allows minimizing the experimental error in any sound field.

Technical features

The invention is about the development of a device and its methodology for measuring the active and reactive sound intensity from the impedance computation. The active intensity is calculated directly in the frequency domain multiplying the complex impedance and power spectrum of the air particle velocity. A second line of post-processing is applied to obtain the overall complex sound intensity. The overall active intensity is calculated as the sum of each frequency component of the its spectrum, while the overall reactive intensity is obtain as the difference between the overall apparent intensity and the overall active intensity.

Possible Applications

  • Pressure-velocity audiometry;
  • Monitoring and control of complex sources (noise control, condition monitoring of industrial machines);
  • Environmental and architectural acoustics;
  • Sound Engineering, music, virtual reality and robotics.


  • Minimization of the experimental error in any acoustic field;
  • Unambiguous and physicly correct definition of the complex sound intensity based on the impedance computation;
  • Calculation of the spectral distribution of the radiative and oscillatory forms of acoustic energy;
  • Calculus of the total reactive intensity.