Four new versions of an acoustic structuring test were developed, administered, and analyzed in order to produce better tests and to contribute to better understanding of the abilities measured by these tests. The tests consist of tape recordings of patterns of musical notes played on an electric organ or an acoustic guitar. Item analyses and factor analyses were used in the studies of these tests, and comparisons were made with earlier test forms. Several different item formats were used. The acoustic structuring tests were correlated with verbal and spatial ability tests, but the results of different studies appeared to conflict with each other. Seven hypotheses concerning characteristics of items that might contribute to item difficulty were studied. Items were categorized with respect to these seven characteristics, and regression analyses were conducted to find the effect of these various item characteristics. (Nine pages of music which illustrate the test items are appended.) (CTM)