Abstract:
In this thesis, a noisy speech enhancement method based on noise compensation
performed on short time magnitude as well phase spectra is presented unlike the
conventional spectral subtraction method. Here, the noise estimate to be subtracted
from the noisy speech spectrum is proposed to be determined exploiting the low
frequency regions of noisy speech of current frame rather than depending only on
the initial silence frames. We argue that this approach of noise estimation o ers the
capability of tracking the time variation of the non-stationary noise thus resulting
in a noise compensated magnitude spectrum. By employing the noise estimates
thus obtained, a procedure is formulated to compensate the distortion in the phase
spectrum,which is kept unchanged in the typical speech enhancement methods. The
noise compensated phase spectrum is then recombined with the noise compensated
magnitude spectrum to produce a modi ed complex spectrum thus synthesizing an
enhanced frame. Extensive simulations are carried out using NOIZEUS database
in order evaluate the performance of the proposed method. It is shown in terms of
objective measures, spectrogram analysis and informal subjective listening test that
the proposed method consistently outperforms some of the state-of-the-art methods
of speech enhancement from noisy speech corrupted by white or train or babble
noise of very low levels of SNR.
