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Abstract. This study investigated the potential of using acoustic tomography for detecting internal decay in high-value hardwood trees in the forest. Twelve black cherry (Prunus serotina) trees that had a wide range of physical characteristics were tested in a stand of second-growth hardwoods in Kane, PA, using a PiCUSW Sonic Tomograph tool. The trees were felled after the field test and a disc from each sampling height was cut and subjected to laboratory evaluations. It was found that acoustic tomography underestimates heartwood decay when it is the major structural defect in the trees. However, when an internal crack is present in the tree trunk, the acoustic tomography tends to overestimate the size of the defects. In the presence of ring shake in the cross-section, the acoustic shadows resemble the influence of both extensive heartwood decay and lateral cracks. These findings highlight the importance of determin ing the nature of structural defects when assessing hardwood trees using the acoustic tomography technique. Results from this study offer insights that may be used to improve the interpretation algorithm embedded in the tomography software