Patent ID: 7346499

Claim:
A method for extending line spectral frequencies of a narrowband speech signal with a frequency range to line spectral frequencies of a wideband speech signal comprising a highband frequency range and the frequency range of the narrowband speech signal, the method comprising: Deriving line spectral frequencies for the highband frequency range of the wideband speech signal by applying a matrix obtained by training to line spectral frequencies of wideband speech signals in the frequency range of the narrowband speech signal, to the line spectral frequencies of the narrowband speech signal; Mapping the line spectral frequencies of the narrowband speech signal to line spectral frequencies of the wideband speech signal in the frequency range of the narrowband speech signal; Combining the line spectral frequencies for the highband frequency range with the line spectral frequencies of the narrowband speech signal to yield a combined signal, wherein the matrix is selected from a list of predetermined matrices based on reflection coefficients obtained from wideband linear prediction coefficients; and synthesizing speech using said combined signal.