The present invention relates to a method for synthesizing a speech signal; comprising obtaining a speech sequence input signal comprising semantic content corresponding to a speaker's utterance; analyzing the input speech sequence signal to obtain a first sequence of feature vectors for the input speech sequence signal; synthesizing a second sequence of feature vectors different from and based on the first sequence of feature vectors; generating an excitation signal and filtering the excitation signal based on the second sequence of feature vectors to obtain a synthesized speech signal wherein the semantic content is obfuscated.