Abstract: Apparatus is provided for acoustically logging earth formations surrounding a borehole containing a known fluid, and includes a downhole tool adapted for longitudinal movement through the borehole, an acoustic transducer assembly for transmitting and receiving acoustic pulse energy, and extendable arms mounting the acoustic transducer assembly on the tool and adapted for lateral extension therefrom for positioning the acoustic transducer assembly in contact with the borehole wall. The acoustic transducer assembly further includes acoustic transducer means for generating acoustic pulse energy for coupling into the borehole fluid substantially free of acoustic ringing and directed an axis generally normal to the borehole wall surface.