Apparatus is provided for lipolysis and body contouring of a subject. The apparatus includes a housing adapted for placement on tissue of the subject. The apparatus also includes a plurality of acoustic elements disposed at respective locations with respect to the housing, including at least a first and a second subset of the acoustic elements, wherein the first subset is configured to transmit energy in a plane defined by the housing, such that at least a portion of the transmitted energy reaches the second subset. Other embodiments are also described.
