Field tests have been conducted with an experimental sidewall acoustic logging instrument. The entire acoustic section, consisting of a transmitting transducer and two receiving transducers is contained in a pad approximately two feet in length. This acoustic pad is mounted so as to maintain contact with the borehole wal I and is equipped with a hydraulic retractor. Mounted on the same carrier but contacting the opposite side of the borehole is a conventional epithermal sidewall neutron pad. This configuration yields a simultaneous recording of an acoustic interval transit time curve, a neutron porosity curve and a caliper curve. The receiver spacing is 6.0 inches, producing an acoustic interval transit time curve with much sharper interface resolution than that obtained from a conventional acoustic logging tool. This fine resolution is useful in recognizing thin interbedded strata and finding horizontal fractures. The system also has unique advantages for studying the characteristics of the received acoustic waves. Due to the very short transmitter to receiver spacing, the shear wave is more readily identifiable than with conventional acoustic logging systems. Examples are shown of logs made under various conditions and results are discussed.