An acoustic transducer assembly includes: a carrier configured to be disposed in an earth formation, the carrier having a carrier axis; an array of transducer elements forming at least a semicircular shape, the array configured to emit acoustic signals in a radial direction relative to the carrier axis; and a circuit coupled to the array and configured to actuate a subset of the transducer elements and emit an acoustic beam therefrom, the circuit configured to actuate the subsets as a phased array to electronically rotate the acoustic beam about the carrier axis.