Patent ID: 8396717

Claim:
A speech encoding apparatus, comprising: a first encoder that encodes a low band spectrum having a lower band than a threshold frequency of a speech signal; a flattening circuit that flattens the low band spectrum using an inverse filter with inverse characteristics of a spectral envelope of the speech signal; and a second encoder that encodes a high band spectrum having a higher band than the threshold frequency of the speech signal using the flattened low band spectrum, wherein the second encoder modifies the flattened low band spectrum such that a dynamic range of the flattened low band spectrum is adjusted to be closer to a dynamic range of the high band spectrum and encodes the high band spectrum using the modified low band spectrum, and the second encoder modifies the flattened low band spectrum using an encoding candidate that decreases a dynamic range preferentially over an encoding candidate that increases the dynamic range, among a plurality of encoding candidates.