Experimental study of a fractal acoustical cavity

The resonance properties of a prefractal cavity are studied in an acoustica l transmission experiment. Resonance frequencies and quality factors are me asured 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 becaus e of their weak coupling with the acoustic excitation and detection. The me asurement of the quality factor of the acoustic resonances confirms the exi stence of increased damping due to the irregular shape of the cavity. This constitutes the first experimental evidence for the damping power of fracta l structures. (C) 1999 Acoustical Society of America. [S0001-4966(99)04503- 8].