The ICTCA conference provides an interdisciplinary forum for active researchers in academia and industry who are of varying backgrounds to discuss the state-of-the-art developments and results in theoretical and computational acoustics and related topics. The papers presented at the meeting cover acoustical problems of common interest across disciplines and their accurate mathematical and numerical modelling.The present book collects papers that were presented at the 4th meeting and printed in the Journal of Computational Acoustics. There are about 120 full research articles on various subjects, such as wave propagation theory and numerical modelling, sound propagation, vibrations and noise generation, underwater acoustics, engineering seismology, ultrasonic field synthesis and modelling, as well as computational methods, inverse problems and tomography, shallow water acoustics and environmental/bottom parameter extraction. A CD-Rom is attached that allows readers to browse through articles and print those of interest to them.