Speech enhancement from noise: a regenerative approach
Speech Communication
A noise reduction method for signals from nonlinear systems
Conference proceedings on Interpretation of time series from nonlinear mechanical systems
Nonlinear time series analysis
Nonlinear time series analysis
Prewhitening for rank-deficient noise in subspace methods for noise reduction
IEEE Transactions on Signal Processing - Part I
MMSE whitening and subspace whitening
IEEE Transactions on Information Theory
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Based on recently observed nonlinear dynamic features of human speech, the local projection (LP) method, originally developed for noisy chaotic time series, is generalized and adapted to the enhancement of Chinese speech. The analysis of minimum embedding dimensions estimated by the false nearest neighbor algorithm shows that all the basic phonemes and syllables in Chinese can be faithfully embedded in some low-dimensional phase space. Over-embedding is applied to reconstruct the dynamics of continuous speech in some extended phase space of higher dimension, thus solving the problem of nonstationarity in continuous speech. A generalization of the LP method, named the local subspace method, is presented for speech enhancement in the phase space. It is demonstrated that, the local subspace method is essentially an extension of the well-known linear subspace technique in the local phase space, and the LP method is the least square case of this generalization. Noise reduction is then carried out in the local phase space. Results show that the LP method, with 2 or 3 iterations, achieves better performances than the local subspace method. For both isolated and continuous speech with additive white noise, experiments show the superiority of the LP method over two other popular algorithms.