(19)
(11) EP 0 557 940 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
23.03.1994 Bulletin 1994/12

(43) Date of publication A2:
01.09.1993 Bulletin 1993/35

(21) Application number: 93102794.0

(22) Date of filing: 23.02.1993
(51) International Patent Classification (IPC)5: G10L 9/14
(84) Designated Contracting States:
DE FR GB

(30) Priority: 24.02.1992 JP 35881/92

(71) Applicant: NEC CORPORATION
Tokyo (JP)

(72) Inventor:
  • Serizawa, Masahiro, c/o NEC Corporation
    Minato-ku, Tokyo (JP)

(74) Representative: VOSSIUS & PARTNER 
Postfach 86 07 67
81634 München
81634 München (DE)


(56) References cited: : 
   
       


    (54) Speech coding system


    (57) An input speech signal is splitted into a time section and the splitted signal is generated as a speech vector and LPC coefficient sets are developed by linear prediction analysis for every time section of the speech vector. The speech vector is weighted based on the developed LPC coefficient sets, then a plurality of the weighted speech vectors are connected and the connected speech vector having a predetermined frame length is generated. An excitation codevector whose weighted synthesized signal is the most similar to the weighted speech vector is determined among from a plurality of excitation vectors each having the frame length which are previously stored as a sound source. A plurality of adaptive codevectors each having the frame length and obtained by cutting out a sound source signal produced from the determined excitation vectors at predetermined timing points are stored in an adaptive codebook (145). An adaptive codevector whose weighted synthesized signal is the most similar to the weighted speech vector is determined among from the plurality of adaptive codevectors.






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