19th Asia-Pacific Vibration Conference (APVC2021)

429 / 2022-08-02 10:25:32

Reconstruction of granular bead motion based on acoustic holography

Granular chain; motion reconstruction; acoustic holography; sound pressure; impulse response function

In earlier research, the theory of acceleration reconstruction for granular beads, using acoustic holography,  was established. To verifiy the feasibility and accuracy of the theory, experiments in both noisy and anechoic environments were conducted in this study. Eight microphones were amounted at fixed positions in the acoustic field to measure sound pressure radiated by 8 granular beads. The amplitudes of sound pressure in experiments are similar to theoretical predictions but different in shape and details, which mainly caused by reflected waves. The experiment in an anechoic chamber eliminates the influence of the wave reflected by the wall, but the sound pressure signals are still affected by waves reflected by the microphone holder, bead support plates, and even the beads themselves. Thus, the theoretical unit impulse response function must be replaced by an experimentally measured unit impulse response.