Piezoelectric ceramic polymer composites with 1-3 connectivity (i.e., parallel rods in polymer) using lead zirconate titanate and epoxy have been fabricated with different ceramic rod widths. The velocity of sound was measured for these composites using the Time-Delay technique. The values of acoustic impedance obtained by this method are compared with the results determined by the Resonance technique. The electromechanical coupling coefficient k(t) and planar coupling coefficient k(p) were determined from the thickness mode resonance and planar mode resonance peaks. The effect of addition of phenolic microballoons on these composites was also investigated. The microballoons had little effect on the acoustic impedance; however, they considerably improved the values of k(t) and k(p).