  In a hybrid speech model, both voiced and unvoiced components can coexist in
a segment. Often, the voiced speech is regarded as the deterministic component,
and the unvoiced speech and additive noise are the stochastic components.
Typically, the speech signal is considered stationary within fixed segments of
20-40 ms, but the degree of stationarity varies over time. For decomposing
noisy speech into its voiced and unvoiced components, a fixed segmentation may
be too crude, and we here propose to adapt the segment length according to the
signal local characteristics. The segmentation relies on parameter estimates of
a hybrid speech model and the maximum a posteriori (MAP) and log-likelihood
criteria as rules for model selection among the possible segment lengths, for
voiced and unvoiced speech, respectively. Given the optimal segmentation
markers and the estimated statistics, both components are estimated using
linear filtering. A codebook-based approach differentiates between unvoiced
speech and noise. A better extraction of the components is possible by taking
into account the adaptive segmentation, compared to a fixed one. Also, a lower
distortion for voiced speech and higher segSNR for both components is possible,
as compared to other decomposition methods.
