10. The apparatus according to claim 1 , wherein a sort order of the speech unit waveforms stored in the waveform memory is optimized based on a frequency of a combination of at least two speech units continuously appearing in training data.
1. An apparatus for synthesizing a speech of an input phoneme sequence, comprising: a waveform memory configured to store a plurality of speech unit waveforms; an information memory configured to correspondingly store speech unit information and an address of each of the plurality of speech unit waveforms stored in the waveform memory; a selector configured to select a speech unit sequence corresponding to the input phoneme sequence by referring to the speech unit information stored in the information memory; an acquisition unit configured to acquire a speech unit waveform corresponding to each speech unit of the speech unit sequence from the waveform memory by referring to the address stored in the information memory; and a concatenation unit configured to generate the speech by concatenating the speech unit waveform acquired by the acquisition unit; wherein the acquisition unit copies at least two speech unit waveforms from a continuous region of the waveform memory onto a buffer by one access, a data quantity of the speech unit waveforms being less than or equal to a size of the buffer, the speech unit waveforms corresponding to at least two speech units included in the speech unit sequence.