Patent ID: 7912710

Claim:
A method for changing reproduction speed of speech sound, comprising: storing an input sound signal in a buffer; leaving a sound signal from the buffer as it is or extending the sound signal from the buffer in a sound section where a power of the input sound signal exceeds a threshold value; and leaving the sound signal from the buffer as it is, compressing the sound signal from the buffer, or deleting the sound signal from the buffer, in a no-sound section, so that the reproduction speed of speech sound is changed, wherein a speech head protection section is set prior to the sound section being set to be a storing amount of the buffer if the storing amount of the buffer is less than a designated amount, the speech head protection section is set to be the designated amount if the storing amount of the buffer is greater than the designated amount, compression or deletion of the sound signal is adjusted by a compression ratio or prevented if there is the sound section in the speech head protection section, so that speech head protection is performed, a pause holding section is set after a speech end protection section having a designated length and following the sound section is ended, and a length of the pause holding section is set corresponding to the length of the speech head protection section.