Subspace techniques in speech enhancement

This paper concerns speech enhancement. Speech is first modelled and then model parameters used to design a Kalman smoother to reduce the background noise. The 4SID (subspace state space system identification), DOA (direction-of-arrival) and polynomial techniques are described within a common subspace state space framework, and assumptions for each technique stated. It is shown that 4SID methods make least assumptions about the data, provide detailed spectra for the vocal tract, and can be used effectively for speech enhancement when combined with a Kalman smoother. An iterative technique is also possible.