Fecha de publicación: 04/04/2003 Fuente: WIPO "miel" 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 M nb area coefficients from the partial correlation coefficient, and extracting M wb area coefficients using interpolation. Wideband parcors are computed from the M wb area 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 M nb area coefficients are converted to log-area coefficients for the purpose of extracting, through shifted-interpolation, M nb log-area coefficients. The M wb log-area coefficients are then converted to M wb area coefficients before generating the wideband parcors.