PURPOSE: To instantaneously follow speech speed change of an output sound to the operation by a receiver.

CONSTITUTION: This device is provided with a section division processing part 11, a pitch period extraction process part 12, a pitch section division processing part 13 being analysis means based on several attributes of the speech sound input data on an input terminal 10, and original sound data/section information buffer part 14 being a speech sound input data analysis information storage means, a speech speed setting part 17 being a speech speed control information generation means by the operation of the receiver, an output buffer part 19 temporarily storing the speech speed change sound data formed beforehand and being a speech speed revision sound storage means whose storage capacity is a prescribed amount or below, a soundless section prolongation process part 15, a pitch section prolongation processing part 16 and a speech speed revision sound data synthesis part 18 reading out analysis information from the original data/section information storage buffer part 14 and performing a synthesis processing the analysis information based on the information of a prolongation ratio and as speech speed change sound forming means of a speaker.