Telecommunication systems and human-machine interfaces have begun using multiple microphones and loudspeakers to render interaction more lifelike and efficient. This raises acoustic signal processing problems under multiple-input multiple-output (MIMO) scenarios, encompassing distant speech acquisition, sound source localization and tracking, echo and noise control, source separation, and speech dereverberation, among others. The book opens with an acoustic MIMO paradigm, establishing fundamentals and linking acoustic MIMO signal processing with classical signal processing and communication theories. The second part of the book presents a novel analysis of acoustic applications carried out in the paradigm to reinforce the fundamentals of acoustic MIMO signal processing.