Soft Computing (SC) techniques have been recognized nowadays as attractive solutions for modeling highly nonlinear or partially defined complex systems and processes. These techniques resemble biological processes more closely than conventional (more formal) techniques. However, despite its increasing popularity, soft computing lacks a precise definition because it is continuously evolving by including new concepts and techniques. Generally speaking, SC techniques encompass two main concepts: approximate reasoning and function approximation and/or optimization. They constitute a powerful tool that can perfectly complement the well-established formal approaches when certain aspects of the problem to solve require dealing with uncertainty, approximation and partial truth. Many real-life problems related to sociology, economy, science and engineering can be solved most effectively by using SC techniques in combination with formal modeling. This book advocates the effectiveness of this combination in the field of speech technology which has provided systems that have become increasingly visible in a wide range of applications.

Speech is a very complex phenomenon involving biological information processing system that enables humans to accomplish very sophisticated communication tasks. These tasks use both logical and intuitive processing. Conventional ‘hard computing’ approaches have achieved prodigious progress, but their capabilities are still far behind that of human beings, particularly when called upon to cope with unexpected changes encountered in the real world.

Therefore, bridging the gap between the SC concepts and speech technology is the main purpose of this book. It aims at covering some important advantages that speech technology can draw from bio-inspired soft computing methods. Through practical cases, we will explore, dissect and examine how soft computing complement conventional techniques in speech enhancement and speech recognition in order to provide more robust systems.