This report evaluates an adaptive microphone array which facilitates a simple built-in calibration to the environment and instrumentation. The method has been suggested for use in hands-free mobile telephones for both speech enhancement and acoustic echo-cancellation as well as speech recognition. The scheme has several advantages such as a simple calibration procedure, directed jammer suppression, versatile robust beamforming and reduced target signal distortion. The analysis employs noncausal Wiener filters yielding compact and effective theoretical suppression limits.