Patent ID: 8433564

Claim:
A method of reducing a noise component from a speech signal, the method comprising the steps of: a) processing a frame of a windowed speech signal x(k), which is a combination of a speech signal s(k) and a noise signal n(k) such that x(k)=s(k)+n(k); b) applying a Fourier Transform (F.T.) to x(k) to obtain X(e jw )=S(e jw )+N(e jw ), where X(e jw ) is a spectrum of the frame of the windowed speech signal, where S(e jw ) is a spectrum the speech signal, where N(e jw ) is a spectrum of the noise signal, and where X(e jw ) includes one or more frequency bands; c) obtaining an energy ratio (E R ) of low frequency energy (E LF ) to total energy (E TOT ) with both E LF and E TOT obtained from the F.T. in part b, above; d) calculating an exponential average of the energy ratio (E R — AVG ) using the equation E R — AVG =α( E R — AVG )+(1−α) E R wherein α is a constant value in the range of 0.75 and 0.95; e) if the E R — AVG is greater than an adaptive threshold, deciding that the frame of the windowed speech signal has wind noise, and calculating an average estimated energy of the frame E F — AVG by the equation E F — AVG =β(E F — AVG )+(1−β)E F , wherein β is a constant value in the range of 0.75 and 0.95, and where E F is an estimated energy of the frame of the windowed speech signal; and if the E R — AVG is less than the adaptive threshold, wind is said to be absent; f) calculating a power spectral density of the frame of the windowed speech signal by the equation {circumflex over ( S )}( e jw )= X ( e jw )−μ( e jw ) where α( e jw ) is an average value of N ( e jw ); and g) finding a signal to noise ratio (SNR) for each frequency band by subtracting an average noise power estimation from the power spectral density of the frame of the windowed speech signal; and calculating gains for each frequency band, wherein gains are linear estimators based upon the SNR for each frequency band.