SPEECH CODER USING A NON-UNIFORM PULSE TYPE SPARSE EXCITATION CODEBOOK

An excitation codebook 351 includes a plurality of codevectors each generated with pulse positions and amplitudes obtained by training such as to reduce the distance between the codevector and training speech data. The excitation codebook 351 further includes a plurality of sparse codevectors each generated with the pulse number, pulse positions and amplitudes obtained by training such as to reduce the distance between the codevector and training speech data, the individual codevectors having different pulse numbers.