This book gives a solution for hands-free mobile phone users, some of the annoying disturbance faced by the user during his teleconference or in a hands-free mode is been addressed and an optimized solution is been presented. The spectral subtraction using a minimum statistics approach has been introduced that eliminates the conventional voice active detector. This technique is capable of tracking non-stationary noise signals and also proved to be efficient in terms of performance and computationally complexity. The book also shows the importance of using first order adaptive differential microphone arrays. This helps in reducing the reverberation effect caused during hands-free mode. The two unique techniques have been successfully integrated and developed it into a new robust algorithm that gives an optimal solution to the hands-free applications.