  Sound propagation in water-saturated granular sediments is known to depend on
the sediment porosity, but few data in the literature address both the
frequency and porosity dependency. To begin to address this deficiency, a
fluidized bed technique was used to control the porosity of an artificial
sediment composed of glass spheres of 265 {\mu}m diameter. Time-of-flight
measurements and the Fourier phase technique were utilized to determine the
sound speed for frequencies from 300 to 800 kHz and porosities from 0.37 to
0.43. A Biot-based model qualitatively describes the porosity dependence.
