Improving the acoustical environment is critical in aeronautics. Airports and aeronautical systems manufacturers are facing ever-increasing demands to reduce noise levels. Aeronautical applications require the use of high quality microphones with a large dynamic range, sometimes in large arrays. These arrays are expensive. The advent of lower cost microphones that meet the users' specifications would dramatically improve the ability of engineers seeking to quantify the acoustic impact of either their designs or their facilities (e.g., airports) and to make data driven decisions to improve any adverse situation. In our Phase-I SBIR, we showed the technical feasibility of a commercially viable, piezoelectric micro-electro-mechanical systems (MEMS) microphones capable of withstanding adverse conditions found in ground testing of the acoustics of aeronautical systems. In the Phase II project, we will implement design changes to improve these sensors. We will develop efficient deep reactive ion etching (DRIE) procedures to increase our yield and lower costs. We will develop scalable packaging techniques so that the devices can be economically assembled into a completed device. Finally, the reliability and robustness of these microphones will be determined. Each of these tasks will advance us toward our goal of producing a commercially viable product with outstanding acoustical performance.