This experimental study investigates the use of Rayleigh waves for crack detection in structural elements. Receiver arrays measure surface accelerations at various locations with respect to a vertical slot cut into a thin Plexiglas sheet. Two-dimensional Fourier transform calculations provide Rayleigh wave dispersion and energy with respect to various slot depths. In addition, autospectrum calculations aid in defining slot location. It is shown that slots reflect short wavelengths and allow the transmission of long wavelengths. Slot location is easily identified from autospectrum measurements; however, accurate determination of slot depth is dependent on the aperture function of the array.