Sound insulation measurement of building components combining diffuse acoustic field excitation and near-field acoustic holography reconstruction

A method for measuring the airborne sound insulation of building components combining diffuse acoustic field (DAF) excitation and near-field acoustic holography (NAH) radiation intensity reconstruction is proposed. In this method, DAF is first used to excite the vibration of the component and obtain the incident sound power, then the normal sound intensity distribution with high spatial resolution on the surface of the component is reconstructed from the radiation sound pressure field using NAH, and finally, according to the sound intensity distribution, the radiated sound power is calculated and the radiation heat areas are located, so as to realize the measurement of sound insulation and sound insulation defects of components. The experimental research in a sound insulation room shows that under the condition that the test distance and sampling interval are both 0.04 m, the error of the sound insulation measured by this method compared to the sound pressure method is less than 3.3 dB in the 100–5000 Hz frequency band and less than 1.3 dB in the 250–3150 Hz frequency band, and the positioning accuracy of round holes (diameter: 8 mm) and rectangular slots (length: 80 mm, width: 3 mm) is up to the centimeter level. The method has strong stability under the influence of certain amount of reverberation and background noise. When reverberation time in the receiving room increases from 1.0 s to 3.4 s (step size: 0.6 s), and the signal-to-noise ratio decreases from 10 dB to 0 dB (step size: 5 dB), the sound volume measurement errors are within 0.8 dB and 0.3 dB, and the defect location errors are within 0.037 m and 0.035 m. The proposed method helps to improve the measurement capability of sound insulation characteristics of building components in the laboratory, and it is robust to the receiving room test environment.