Abstract: A way of a synthesizing speech by the combination of a Speech coding mode and Formant analysis mode is achieved by segmenting a Formant transition region into portions, according to the linear characteristics of a frequency curve, and storing the Formant information of each portion. Therefrom frequency information of a sound is obtained. Formant information data of a Formant contour to produce speech, is calculated by a linear interpolation method. The frequency and the bandwidth, which are elements of the Formant contour calculated by a linear interpolation method, are sequentially filtered in order to produce a speech signal which is a digital speech signal. The digital speech signal is converted to an analog signal, amplified, and output through a external speaker.