  This paper proposes a method to improve the quality delivered by statistical
parametric speech synthesizers. For this, we use a codebook of
pitch-synchronous residual frames, so as to construct a more realistic source
signal. First a limited codebook of typical excitations is built from some
training database. During the synthesis part, HMMs are used to generate filter
and source coefficients. The latter coefficients contain both the pitch and a
compact representation of target residual frames. The source signal is obtained
by concatenating excitation frames picked up from the codebook, based on a
selection criterion and taking target residual coefficients as input.
Subjective results show a relevant improvement compared to the basic technique.
