Microphone Arrays *
This chapter is about noise reduction using two or more microphones. It focuses on small-scale applications of microphone array technology. Microphones, by nature, have some directionality, and, in some cases, this can be maximized or minimized by the design of the hardware and its electronics. The behavior of a microphone in a sound field is in many ways analogous to that of an electromagnetic antenna, and its performance can be described by polar diagrams in the same way. The chapter looks at system designs that more closely integrate the microphone array design and the algorithm design in order to enhance the quality of the output, even with the most basic signal processing algorithm. In general, a beamforming solution is frequency dependent, so that the output speech may have noticeable spectral coloring, or, even worse, suffer partial cancellation.