Abstract: A passive sonar transducer arrangement includes two steerable array sections (10,11) arranged with the transducers of one section (10) spaced apart from one another by a different distance (d1) from the spacing (d2) between the transducers of the other section (11), the spacing for each section being such that aliasing will occur for at least some steering angles (.THETA..sub.s) and such that the alias beams produced by the two sections of the array will not overlap. Cross-correlation means (12-19) are provided to process the signals received from the sonar transducers of the two sections such that the effects of the alias beams are substantially removed.