| 摘要 |
PURPOSE: To make a manufacturing cost inexpensive by changing sound pressures to be outputted from a sounding body while changing frequencies of rectangular waves to be inputted from a microcomputer to the sounding body and simplifying a manufacturing process. CONSTITUTION: The rectangular wave having a desired frequency is generated by activating a timer 1a to be inputted to a sound body 3 and then the voice having a sound pressure corresponding to a frequency D. Next, values of the timer 1 are changed to time widths of rectangular waves equivalent to half cycles of frequencies E, F, G, etc., corresponding to desired sound pressures of the outputs from the sound body 3. Thereafter, after the elapse of a delay time, rectangular waves are generated by activating the timer 1a every proper time and by making an output port reverse with a set time to be outputted from the sounding body 3 as the voice having sound pressures corresponding to frequencies of the rectangular waves. Thus, the vaying of sound pressures is realized by a software by using the attenuation characteristic and the envelop characteristic of a sound volume. |
