Abstract
In this paper, we propose a system to transmit the warning information by the sound of a sport for the deaf and hard hearing. The proposed system consists of following five elements: (a) a capacitor microphone for measuring a sound, (b) a biquad filter circuit for extracting only a warning sound, (c) a V-F conversion circuit, (d) a F-V conversion circuit, and (e) a vibration sensor. The following results were obtained in the experiment. In order to extract only the signal component of a whistle from a measurement signal, the biquad filter circuit was used, and its usefulness was shown. As a result of carrying out V-F conversion of the signal component of a whistle, it was confirmed that the fixed pulse wave corresponding to the frequency of a whistle was output. When the output signal from the V-F conversion was converted to F-V, the vibration sensor operated with an output signal (voltage) proportional to the number of pulses. The frequency of the sound emitted from a whistle depends on the structure of the whistle (e.g. whistles containing a cork). Furthermore, the size of field differs according to sporting events. Therefore, it is necessary to modulate the gain (sensitivity) of a signal by adjusting a resistor and a capacitor used on the biquad filter circuit in such an environment. The system can be adjusted by using a potentiometer and a trimmer capacitor.
