| 摘要 |
A noise reduction system and device, and a mobile radio station. Known is a combined Zelinski-spectral subtraction system (1) for noise reduction in a combined speech signal (a(t)) in which signals are recorded with a plurality of microphones (5, 6, 7), using a Wiener filter (10) for estimation of the combined speech signal (a(t)'). In the known system (1) sums and differences of all combinations of speech signals are formed, it being assumed that the differences comprise noise only. Furthermore, a two stage estimation process is carried out, giving rise to considerable estimation errors. An alternative combined Zelinski-spectral subtraction system (1) is proposed, giving rise to fewer estimation errors and being more efficient from a computational point of view. In the Zelinski system, spectral subtraction is carried out on a combined cross spectrum ( PHI cc). Then, on a speech segment by speech segment basis, filter coeffients for the Wiener filter (10) are determined from a combined auto power spectrum ( PHI ac) and the thus corrected combined cross power spectrum ( PHI cc'). The spectral subtraction is carried out on a lower part of the frequency range only, thereby not introducing unneccesary artefacts. |
