The measurement microphones of today are the results of almost 50 years of continuous optimization of production methods based on precision mechanics. Scientists have searched for new ways of measuring sound, which can reach the performance of the condenser microphone, but so far have not succeeded! However, applying new materials and production methods, the window of achievable specifications of condenser microphones can be widened. Combining the accuracy and reliability of silicon micro machining with the experience gained on traditional measurement microphones, unique new features can be added to the range of microphones. As a first result of such efforts, a new microphone unit, the multifield microphone, has been developed. The multifield microphone has a ‘‘flat’’ frequency response in all sound fields, i.e., pressure field, diffuse field, or free field (when the sound comes from different angles of incidence). This results in higher accuracy in most measurement situations, where the sound field is nonidealized.