A two-step noise reduction technique

The paper addresses the problem of single microphone speech enhancement in noisy environments. Common short-time noise reduction techniques proposed in the art are expressed as a spectral gain depending on the a priori SNR. In the well-known decision-directed approach, the a priori SNR depends on the speech spectrum estimation in the previous frame. As a consequence, the gain function matches the previous frame rather than the current one which degrades the noise reduction performance. We propose a new method, called the two-step noise reduction (TSNR) technique, which solves this problem while maintaining the benefits of the decision-directed approach. This method is analyzed and results in voice communication and speech recognition contexts are given.