This volume contains forty-one papers presented at the Eleventh International Symposium on Acoustical Imaging held on 4-7 Ma~ in Monterey, California. The objective of this conference series is to bring together workers in diverse areas and applications of Acoustical Imaging for interaction and exchange of ideas. People working in other aspects of scalar wave theory and applications also benefit from this series. The papers presented here demonstrate continued growth in the activity of this field. In this conference there was emphasis on New Techniques, Acoustic Tomography, Tissue Characterization, Signal Processing, Inversion Techniques, and Transducers and Arrays. The success and stimulation of the conference and of the papers presented in this volume is owed, of course to the authors and participants. Many thanks are due to the authors and their co-workers for their diligence and enthusiasm in performing their research, preparing their manuscripts and presenting their results. The editor would like to express his appreciation to each and every one of them.