A system, apparatus and method for processing this flat articles, such as semiconductor wafers, with acoustical energy. In a cleaning process, the inventive system, apparatus and method can remove particles from both sides of a wafer more efficiently and effectively. in one aspect, the invention is a system for processing flat articles comprising: a rotatable support for supporting a flat article; a first dispenser for applying liquid to a first surface of a flat article on the rotatable support; a second dispenser for applying liquid to a second surface of a flat article on the rotatable support; a first transducer assembly comprising a first transducer for generating acoustic energy and a first transmitter acoustically coupled to the first transducer, the first transducer assembly positioned so that when the first dispenser applies liquid to the first surface of a flat article on the rotatable support, a first meniscus of liquid is formed between a portion of the first transmitter and the first surface of the flat article; and a second transducer assembly comprising a second transducer for generating acoustic energy and a second transmitter acoustically coupled to the second transducer, the second transducer assembly positioned so that when the second dispenser applies liquid to the second surface of the flat article on the rotatable support, a second meniscus of liquid is formed between a portion of the second transmitter and the second surface of the flat article.