Patent ID: 7003461

Claim:
In a computer device for speech synthesis, a method for searching a codebook of excitation vectors to identify a selected excitation vector for CELP (code-excited linear prediction) coding comprising: receiving an input speech signal; computing a metric M i based on the input speech signal and a signal synthesized by an excitation vector v i ; repeating the computing step for each excitation vector in the codebook; and identifying a minimum metric (M min ) from among the computed M i 's, the excitation vector associated with M min being the selected excitation vector used to produce synthesized speech, wherein the computing step includes computing a correlation quantity between a target vector signal and an impulse response comprising: accessing elements R i of a first vector (R) stored in a first area of a memory component of the computer device and representative of the target vector signal; accessing elements I i of a second vector (I) stored in a second area of the memory component and representative of the impulse response; computing ⁢ ⁢ a ⁢ ⁢ vector ⁢ ⁢ F ⁢ ⁢ 1 = [ 0 ⋯ ⋯ 0 R 0 ⋮ R 0 R 1 ⋮ ⋱ ⋮ 0 R 0 ⋮ R 0 R 1 ⋯ ⋯ R ( 2 s - 1 ) ] × [ I 2 s - 1 ⋮ ⋮ ⋮ I 0 ] ; and computing ⁢ ⁢ a ⁢ ⁢ vector ⁢ ⁢ F ⁢ 2 = ∑ n = 2 s Frm , step ⁢ ⁢ 4 ⁢ ⁢ { [ 0 ⋯ ⋯ 0 R n ⋮ R n R n + 1 ⋮ ⋱ ⋮ 0 R n ⋮ R n R n + 1 ⋯ ⋯ R n + ( 2 s - 1 ) ] × [ I 2 s - 1 ⋮ ⋮ ⋮ I 0 ] + ∑ m = n + ( 2 s - 1 ) l = 0 l , step ⁢ ⁢ 4 m , step ⁢ - 4 m - 2 × ( 2 s - 1 ) > 0 ⁢ ⁢ [ I ( m - ( 2 s - 1 ) ) - ( 2 s - 1 ) ⋯ I ( m - ( 2 s - 1 ) ) ⋮ ⋮ ⋮ ⋮ I ( m - ( 2 s - 1 ) ) ⋯ I m ] × [ R l + ( 2 s - 1 ) ⋮ ⋮ R l ] } , where s>1 and Frm is a framesize, wherein the vectors F 1 and F 2 together are representative of the correlation quantity.