Introduction

Ever since the invention of telephone systems, sound signal acquisition has become an essential part of acoustic and speech processing. Traditionally, sound signals are recorded and processed with the use of a single microphone; but this way of acquisition suffers significant limitations: not only the sound spatial realism is lost but also the flexibility in processing the recorded signal. Indeed, extracting the signal of interest from the noise, reverberation, and competing sources, is confined to a small family of techniques. To preserve the sound fidelity, spatial realism, and increase the processing flexibility in dealing with multiple sources and noise, the concept of microphone arrays has been introduced.