A post-filter for wideband speech beamforming in automotive application
Huajun Yu, Tim Fingscheidt · 2010
Microphone arrays and beamforming for car applications have gained much attention in the past. While several proposals aim at quite idealistic conditions, our approach intentionally employs low-cost microphones. Moreover, we assume the microphone array to be integrated into the head-unit of the car. Although from an acoustical perspective this is not an ideal location, it is yet very attractive since it omits further wiring and offers a compact and optimized solution. To achieve the required level of directivity and noise reduction in car noise, the a priori noise field of diffuse noise is exploited. A new postfilter estimation using an adaptive smoothing factor along with an estimation quality indicator is proposed which is well suited for low-cost microphones. Meanwhile, an intrusive instrumental evaluation methodology will be introduced. We will show that a significant level of noise attenuation can be achieved, while the quality of the speech component will be improved compared to the state-of-the-art.