PURPOSE: To perform the detailed explanation of operation and function and the instruction of operation without using a large display device by informing of related information by means of a voice according to user's operation.

CONSTITUTION: The train of phonetic symbols composed of reading information and accent information is inputted in a speech synthesizing part 12 by the control of a CPU 1 and pitch information that is the fundamental cycle of a voice signal changing with time from the accent information in a pitch generating part. A sound source part generates a signal including many higher harmonics such as an impulse and a sawtooth wave and having a period corresponding to the pitch information, simulates the frequency characteristic of a human throat and mouth and generates various kinds of sound signals from the sound source signal. An adder 13 adds a musical sound signal generated in a musical sound generating part 7 to a voice signal generated in the speech synthesizing part 12. The related information is noticed by means of a voice in accordance with user's operation.