This book contains the technical papers presented at the 16th International Symposium on Acoustical Imaging which was held in Chicago, Illinois USA from June 10-12, 1987. This meeting has long been a leading forum for acoustic imaging scientists and engineers to meet and exchange ideas from a wide range of disciplines. As evidenced by the diversity of topical groups into which the papers are organized, participants at the meeting and readers of this volume can benefit from developments in medical imaging, materials testing, mathematics, microsocopy and seismic exploration. A common denominator in this field, as its name implies, is the generation, display, manipulation and analysis of images made with mechanical wave energy. Sound waves respond to the elastic properties of the medium through which they propagate, and as such, are capable of characterizing that medium; something that cannot be done by other means. It is astonishing to realize that acoustic wave imaging is commonly performed over about eight decades of frequency, with seismology and microscopy serving as lower and upper bounds, respectively. The physics is the same, but the implementations are quite different and there is much to learn. The conference chairman and editor wishes to express his appreciation to those who helped run the symposium - namely the Technical Review COIIII1ttee and Session Cbair:aen including Floyd Dunn, Gordon S.