Introduction to the special issue on verification and validation of source and propagation models for underwater sounda).

This joint Special Issue of JASA and JASA Express Letters focuses on underwater sound source and propagation modelling, both of ambient sound as well as sources of relevance to possible effects of sound on aquatic life, and corresponding acoustical metrics. Combining information on the sound field with information on a dose-effect relationship enables estimation of the potential effects. The Special Issue presents a collection of eighteen articles on the following topics: (1) verification of source and propagation models, (2) validation of source and propagation models, and (3) bioacoustical metrics for assessment of the risk of environmental effects. This special issue demonstrates the need for clear metrics and verification and validation protocols.