An ultrasonic transducer having a membrane and a container having a base and at least one wall element. The one or more wall elements can be situated over at least part of the base to form a cavity that can have an at least partially open end. The open end can be sealed with the membrane and the interior of the container can be maintained at a lower atmospheric pressure than the ambient pressure. Within the container, a piezoelectric flexure can be fixed at one end to a location at a wall element. The other end of the flexure can be in mechanical communication with the membrane, either directly or through a stiffener that is itself in communication with the membrane.