Patent ID: 6941267

Claim:
A speech data compression/expansion apparatus, comprising: a waveform data reference/extraction part for extracting waveform data by referring to an existing waveform dictionary; a use frequency information storage part for accumulating a use frequency used for speech synthesis regarding the extracted waveform data and storing it; a use frequency-based compressed data generation/storage part for compressing the waveform data by changing a compression method gradually in accordance with the use frequency, storing the compressed waveform data in the waveform dictionary, and storing information on the compression method regarding each of the compressed waveform data; and a waveform data expansion part for expanding the compressed waveform data stored in the waveform dictionary, based on the information on the compression method, wherein one or a plurality of predetermined threshold value is determined with respect to the use frequency regarding the waveform data, and in a plurality of use frequency ranges partitioned with the threshold values, waveform data belonging to the use frequency range with a smaller use frequency is compressed by a compression method with a correspondingly increased compression ratio.