Experimental study of a fractal acoustical cavity

The resonance properties of a prefractal cavity are studied in an acoustical transmission experiment. Resonance frequencies and quality factors are measured and compared to theory. All the delocalized modes are detected, and their measured eigenfrequencies closely fit numerical predictions. Most of the localized modes appear to be missing in the experimental spectra because of their weak coupling with the acoustic excitation and detection. The measurement of the quality factor of the acoustic resonances confirms the existence of increased damping due to the irregular shape of the cavity. This constitutes the first experimental evidence for the damping power of fractal structures.