Patent ID: 8275061

Claim:
A spectrum coding apparatus comprising: an acquisition section that acquires a first spectrum which frequency k is in a band of 0≦k<FL; an acquisition section that acquires a second spectrum which frequency k is in a band of 0≦k<FH; an estimation section that estimates a shape of said second spectrum in a band of FL≦k<FH by the following expression D ( k )= D ( k−T ) where D(k) in 0≦k<FL is the first spectrum, D(k) in FL≦k<FH is the estimated second spectrum, and T is a pitch coefficient; and a coding section that codes a pitch coefficient minimizing a distortion between the shape of the estimated second spectrum and the shape of said second spectrum in the band of FL≦k<FH, wherein the pitch coefficient minimizing the distortion maximizes the following: ( ∑ FH - 1 k = FL ⁢ S ⁡ ( k ) · D ⁡ ( k ) ) 2 ∑ FH - 1 k = FL ⁢ D ⁡ ( k ) 2 wherein S(k) is the second spectrum and D(k) is the estimated second spectrum.