Abstract: A method of deriving speech synthesis parameters from an audio signal, the method comprising: receiving an input speech signal; estimating the position of glottal closure incidents from said audio signal; deriving a pulsed excitation signal from the position of the glottal closure incidents; segmenting said audio signal on the basis of said glottal closure incidents, to obtain segments of said audio signal; processing the segments of the audio signal to obtain the complex cepstrum and deriving a synthesis filter from said complex cepstrum; reconstructing said speech audio signal to produce a reconstructed speech signal using an excitation model where the pulsed excitation signal is passed through said synthesis filter; comparing said reconstructed speech signal with said input speech signal; and calculating the difference between the reconstructed speech signal and the input speech signal and modifying either the pulsed excitation signal or the complex cepstrum to reduce the difference between the reconstr