A reanalysis of experimental high-frequency spectra using periodic orbit theory

The data, obtained [R. L. Weaver, J. Acoust. Soc. Am. 85, 1001 (1989)] on high eigenfrequencies of small aluminum blocks, is reanalyzed using improved fitting procedures. If the results are quantitatively different from those published previously, they do not significantly modify the main conclusion that fluctuations of the spectrum on a small scale (involving a few mean eigenfrequency spacings) are well described by the model of Gaussian orthogonal ensemble (GOE) of random matrices. In addition, it is shown that, on a larger scale, the spectrum is correlated due to the existence of periodic classical ray trajectories. In other words, the large scale oscillations of the spectrum yield information on the size and shape of the aluminum blocks.