Vibroacoustic characteristics of light-weighted slabs – Part 2: Measurement-Based Investigation of the Sound Radiation of Suspended Ceilings

In part 1 the development of an appropriate numerical model of a wooden slab - calibrated and model-updated using measurement data - was described and its application for questions of sound-radiation was presented. In this contribution the limits of modal approaches in the spatial domain due to an increasing modal density (already beneath 100Hz in case of light-weighted structures like wooden slabs with suspended ceilings) are discussed in detail. An alternative approach transforming the problem into the wavenumber-domain, where a direct link to physical parameters (like the wavenumber of the bending wave for instance) becomes visible, is advantageous and can be applied also in a higher frequency range. In addition radiation of sound, which occurs for finite structures also beneath the coincidence frequency, can be predicted in the transformed domain out of the velocity-pattern, which could be obtained out of measurements or numerical (FEM) analyses for instance, using Integral Transform Methods. A validation of the method is presented, where both the velocity pattern and the sound pressure-field were measured on a real structure. The radiated sound computed in the transformed domain out of the measured velocity-pattern is compared against the results measured by an intensity probe.      «

In part 1 the development of an appropriate numerical model of a wooden slab - calibrated and model-updated using measurement data - was described and its application for questions of sound-radiation was presented. In this contribution the limits of modal approaches in the spatial domain due to an increasing modal density (already beneath 100Hz in case of light-weighted structures like wooden slabs with suspended ceilings) are discussed in detail. An alternative approach transforming the proble...     »