System for bandwidth extension of narrow-band speech

nb wb wb nb wb wb wb A system and method are disclosed for extending the bandwidth of a narrowband signal such as a speech signal. The method applies a parametric approach to bandwidth extension but does not require training. The parametric representation relates to a discrete acoustic tube model (DATM). The method comprises computing narrowband linear predictive coefficients (LPCs) from a received narrowband speech signal, computing narrowband partial correlation coefficients (parcors) using recursion, computing Marea coefficients from the partial correlation coefficient, and extracting Marea coefficients using interpolation. Wideband parcors are computed from the Marea coefficients and wideband LPCs are computed from the wideband parcors. The method further comprises synthesizing a wideband signal using the wideband LPCs and a wideband excitation signal, highpass filtering the synthesized wideband signal to produce a highband signal, and combining the highband signal with the original narrowband signal to generate a wideband signal. In a preferred variation of the invention, the Marea coefficients are converted to log-area coefficients for the purpose of extracting, through shifted-interpolation, Mlog-area coefficients. The Mlog-area coefficients are then converted to Marea coefficients before generating the wideband parcors.