1. A method of preparing a frame of a digital speech signal for compression comprising the steps of: producing a linear prediction residual for the frame, the linear prediction residual having irregularly spaced dominant peaks; dividing the residual into a series of contiguous, non-overlapping sections, each section containing not more than one dominant peak; deriving an idealized signal having a series of regularly-spaced dominant peaks located in a series of sequential sections; associating each section of the residual with a corresponding section of the idealized signal; calculating a linear continuous warp contour for each residual section based on a subset of possible last sample lag values for each residual section within a subrange of possible last sample lag values for each residual section; and modifying the residual by applying the calculated warp contour to the sections of the residual so that any dominant peak in each section of the residual aligns with the dominant peak in the corresponding section of the idealized signal, whereby dominant pitch peaks of the modified residual are regularly spaced, and no portion of any section of the residual is omitted or repeated in the modified residual.