SPEECH SPEED CHANGING METHOD, AND SPEECH SPEED CHANGING DEVICE

A method for changing reproduction speed of speech sound, includes the steps of: 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; leaving the sound signal from the buffer as it is, compressing the sound signal from the buffer, or extending 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 limited by a designated limited value; and 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.