A Comparison of Sampling Methods for a Standing Tree Acoustic Device

One method of evaluating potential product performance is the use of acoustic tools for identifying trees with high stiffness. Acoustic velocities for 100 standing loblolly pine (Pinus taeda) trees, obtained with the transmitting and receiving probes placed on the same face and opposite faces, were compared. Significant differences in velocity between the two methods were found, with velocity determined using the opposite-face method generally dependent on stem diameter, or the amount of wood through which the stress wave must pass. The only opposite-face method in which the velocities did not vary with dbh was for an assumed flight path where the stress wave traveled from the transmitting probe around the circumference of the stem in the outerwood and then down longitudinally to the receiving probe. Variation in velocities from hit-to-hit was 62% less using the opposite-face method compared with the same-face method. It is recommended to use the circumferential opposite-face (Vel_OC) calculation when determining stress wave velocity for a standing tree.