Abstract: An acoustic wave transducer useful in sonic logging while drilling a borehole through an adjacent earth formation includes an array of transducer elements mounted circumferentially around a drill collar. The elements are bonded in an elastomer ring that is received in an external groove in the collar and are protected by a shield having windows. The elements are electrically connected in parallel so that when excited by an electrical pulse, the elements generate a monopole acoustic wave that propagates out into the formation. When used as a receiver, the electrically connected array of elements detect averaged acoustic waves from the formation around the circumference of the drill collar and have minimum sensitivity to acoustic multipole waves traveling through the drill collar.