Effects of symmetry breaking on statistical properties of near-lying acoustic resonances

Statistical properties of acoustic modes in quartz blocks, measured recently by Ellegaard et al. [Phys. Rev. Lett. 77, 4918 (1996)], are compared with predictions of a random matrix ensemble that incorporates the approximate point-group symmetry of the samples. We observe close agreement between the nearest-neighbor acoustic mode spacing distributions and level spacing distributions predicted for the corresponding matrix ensemble. The single symmetry-breaking parameter of the random matrix ensemble is seen to scale with the size of the symmetry-breaking deformation of the quartz sample.