摘要
Traditional stereo-recording microphones rely on the design of acoustic mechanisms to produce directional characteristics required in recording techniques such as Mid-Side (M-S) and X-Y stereophony. However, conventional systems are generally too large to be mounted on mobile devices. In this report a small general-purpose microphone array system is proposed for stereo recording with mobile devices. By using array signal processing, omnidirectional, dipole, cardioid elements, as required in common two-channel stereophony, can be simulated for recording. In addition, 5.1 surround sound can also be realized with a special microphone arrangement. To synthesize desired beam patterns, optimized beamformers are designed with the aid of least-square and convex optimization techniques. Two-channel stereophonic recording configurations including a broadside array, a curved array, and a 5.1 surround sound array are developed and evaluated with objective and subjective tests. For two-channel stereophonic recording, the results show that the broadside array and curved array outperform the conventional M-S technique. On the other hand, the 5.1 array has achieved similar recording quality as conventional systems.