A method of producing a synthesis signal in a modified discrete cosine transform, MDCT-coded, first frame extending from a frame boundary LPC1 to a frame boundary LPC2, comprising: (a) receiving the MDCT-coded frame extending from the frame boundary LPC1 to the frame boundary LPC2, and (b) decoding the first frame by applying an inverse modified discrete cosine transform, IMDCT, to the first frame to produce between the frame boundaries LPC1 and LPC2 a time-domain signal containing windowing and time-domain aliasing effects; (a) receiving forward aliasing cancellation, FAC, parameters, (b) decoding the FAC parameters to produce a first part of a FAC synthesis signal at the beginning of the first frame and a second part of the FAC synthesis signal at the end of the first frame, by (i) inverse transforming the FAC parameters, and (ii) filtering the inverse transformed FAC parameters using an inverse filter 1/ W 1 (z) with zero initial state for the first part of the FAC synthesis signal and an inverse filter 1/ W 2 ( z) with zero initial state for the second part of the FAC synthesis signal, wherein W 1 (z) is a weighting filter computed from a first LPC filter calculated at the frame boundary LPC1 or from an interpolated LPC filter using both the first LPC filter calculated at the frame boundary LPC1 and a second LPC filter calculated at the frame boundary LPC2, and wherein W 2 ( z) is a weighting filter computed from the second LPC filter calculated at the frame boundary LPC2 or from an interpolated LPC filter using both the first LPC filter calculated at the frame boundary LPC1 and the second LPC filter calculated at the frame boundary LPC2; positioning at the beginning of the first frame a windowed and time-inverted ACELP synthesis from the ACELP frame preceding the first frame and a windowed zero-input response of the ACELP synthesis filter calculated at the frame boundary LPC1; adding (a) the time-domain signal containing windowing and time-domain aliasing effects, (b) the first and second parts of the FAC synthesis signal, (c) the windowed and time-inverted ACELP synthesis, and (d) the windowed zero-input response of the ACELP synthesis filter to form the synthesis audio signal in the first frame in the time domain where time-domain aliasing and windowing effects have been cancelled at the beginning and end of the first frame, and wherein potential discontinuity at the frame boundary LPC1 has been smoothed and perceptually masked by the inverse filters 1/ W 1 ( z) and 1/ W 2 ( z). (a) receiving the MDCT-coded frame extending from the frame boundary LPC1 to the frame boundary LPC2, and (b) decoding the first frame by applying an inverse modified discrete cosine transform, IMDCT, to the first frame to produce between the frame boundaries LPC1 and LPC2 a time-domain signal containing windowing and time-domain aliasing effects; (a) receiving forward aliasing cancellation, FAC, parameters, (b) decoding the FAC parameters to produce a first part of a FAC synthesis signal at the beginning of the first frame and a second part of the FAC synthesis signal at the end of the first frame, by (i) inverse transforming the FAC parameters, and (ii) filtering the inverse transformed FAC parameters using an inverse filter 1/ W 1 (z) with zero initial state for the first part of the FAC synthesis signal and an inverse filter 1/ W 2 ( z) with zero initial state for the second part of the FAC synthesis signal, wherein W 1 (z) is a weighting filter computed from a first LPC filter calculated at the frame boundary LPC1 or from an interpolated LPC filter using both the first LPC filter calculated at the frame boundary LPC1 and a second LPC filter calculated at the frame boundary LPC2, and wherein W 2 ( z) is a weighting filter computed from the second LPC filter calculated at the frame boundary LPC2 or from an interpolated LPC filter using both the first LPC filter calculated at the frame boundary LPC1 and the second LPC filter calculated at the frame boundary LPC2;