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AssigneeSextant Avionique
InventorsDominique Pastor, Gérard Reynaud, Pierre-Albert Breton
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The disclosed method uses the Wiener frequency filtering to suppress noise in noisy sound signals (u(t)). This method includes a preliminary step in which the sound signals (u(t)) to be noise-suppressed are digitized by sampling and subdivided into frames. The method then includes a first series of steps including the creation of a noise model on N frames, the estimating of the spectral density of the noise and of the energy of the noise model and the computing of a coefficient that reflects the statistical dispersion of the noise. It also includes a second series of steps including the computation of the spectral density of the signals to be noise-suppressed fore each frame. The coefficients of the Wiener filter are modified for each successively processed frame, by the parameters determined at the end of the two series of steps, so as to introduce an energy compensation and an adaptive overestimation of the noise.
A method of frequency filtering for the removal of noise from noisy sound signals (u(t)) formed by sound signals mixed with noise signals, the method comprising:
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Speech enhancement, e.g. noise reduction or echo cancellation: noise filtering
Speech analysis techniques or speech synthesis
Term ended 20 Nov 2018 (estimated)
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1. Field of the Invention
The present invention relates to a method of frequency filtering implementing a Wiener filter.
It can be applied especially but not exclusively to noise suppression in sound signals containing speech picked up in noisy environments and more generally to noise suppression in all sound signals.
The invention will be understood more clearly and other features and advantages shall appear from the following description made with reference to the appended figures, of which:
FIG. 1 provides an illustration, in the form of a block diagram, of the main steps of the method according to the invention;
FIG. 2 provides a schematic illustration of a prior art Wiener filter;
The main phases and steps of the method according to the invention shall now be described with reference to the block diagram of FIG. 1. Each block, referenced 0 to 5, represents a phase of the method, which itself can be divided into elementary steps.
Hereinafter, to provide a clear picture and without in any way thereby limiting the scope of the invention, the description shall be set in the context of the processing of noisy speech. As stated here above, it is common practice to consider that the stationary states, especially voicing, are established on durations of 10 to 20 ms, a time interval that is characteristic of the elementary phenomena of speech production and shall be described hereinafter as a “frame”.
As in the prior art, the method of the invention comprises a step for the subdivision into frames of the audiophonic signal to be noise-suppressed or cleared of noise (block 0).