Adaptive Digital Filters presents an important discipline applied to the domain of speech processing. The book first makes the reader acquainted with the basic terms of filtering and adaptive filtering, to further introduce the reader into the field of advanced modern algorithms, some of which represent a contribution of the authors of the book. The work in the field of adaptive signal processing requires the use of a complex mathematical apparatus. The manner of exposition in this book presumes a detailed presentation of the mathematical models, a task done by the authors in a clear and consistent way. The chosen approach enables everyone with a college level of mathematics knowledge to successfully follow the mathematical derivations and descriptions of algorithms in the book. The algorithms are presented by flow charts, which facilitates their practical implementation. The book gives many experimental results and treats the aspects of practical application of adaptive filtering in real systems. The book is useful both to students of undergraduate and graduate studies, and to all of those who did not have an opportunity to master this important science field during their formal education.