  The time-domain cross-correlation of incoherent and random noise recorded by
a series of passive sensors contains the impulse response of the medium between
these sensors. By using noise generated by a can of compressed air sprayed on
the surface of a plexiglass plate, we are able to reconstruct not only the time
of flight but the whole waveforms between the sensors. From the reconstruction
of the direct $A_0$ and $S_0$ waves, we derive the dispersion curves of the
flexural waves, thus estimating the mechanical properties of the material
without a conventional electromechanical source. The dense array of receivers
employed here allow a precise frequency-wavenumber study of flexural waves,
along with a thorough evaluation of the rate of convergence of the correlation
with respect to the record length, the frequency, and the distance between the
receivers. The reconstruction of the actual amplitude and attenuation of the
impulse response is also addressed in this paper.
