Audio encoding device and audio encoding method

A speech encoding apparatus comprising:

• a calculating section that calculates a correlation value for each candidate pulse position using a target signal and a plurality of pulses forming a fixed codebook, and calculates, on a per pulse basis, a representative scalar value of a pulse using a maximum value of the correlation values calculated for the pulse, wherein each representative scalar value corresponds to each pulse;
• a sorting section that sorts the representative scalar values acquired on a per pulse basis, for the plurality of pulses, groups pulses corresponding to the sorted representative scalar values into a plurality of predetermined subsets and determines a first subset to be searched first and a second subset to be searched second among the plurality of subsets;
• and
• a search section that searches the fixed codebook using the first subset and the second subset and acquires a code indicating positions and polarities of a plurality of pulses for minimizing coding distortion,
• wherein the calculating section calculates, as the representative scalar value, the maximum correlation value of each pulse by adding a second highest correlation value multiplied by a predetermined rate to a maximum value of the correlation value on a per pulse basis.