|Budget Amount *help
¥3,580,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥480,000)
Fiscal Year 2007: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2006: ¥1,500,000 (Direct Cost: ¥1,500,000)
This research was carried out to develop sound information notification system by two -channel electrotactile stimulation for hearing impaired persons, considering the use outdoors and indoors. The contents of research were as follows.
1. Sound information was provided with the attention arousal, notifying the direction of the sound source (four states) and the sound category (11 states : four of outdoors and seven of indoors). In the use outdoors, the direction of the sound source (direction) must be informed alertly as fast as possible to avoid dangerous situations. So, we defined two kinds of information on the attention arousal and the direction. While, sound information indoors does not require emergency and so to improve the quality of life of hearing impaired persons (HIP), we defined three kinds of information : attention arousal, the direction, and the sound category.
2. We developed the method to recognize sound information under the actual environments. In the use outdoors, at
first, noise of sound data recorded by using two microphones is reduced via band pass filter. Then, the reduced sound data are separated by BSS. Finally, the separated sound is judged by using six parameters, and when the judged sound is one of four sounds, the direction is estimated. In the use indoors, after noise reduction by SS, each of seven sound categories is estimated as with the case of the use outdoors. Then, the direction is estimated, and sound information is detected. The direction is detected by the difference of amplitudes between two microphones. Judgment of the sound category is done by the calculation of Euclid distance on six parameters between the dictionary pre-recorded sounds and the actual one. Under the noise occurrence, detection ratio of the sound category was 80%, recognition ratio of the direction about 80% of the correct samples was 88%.
3. The detected sound information which corresponds to the 12 stimulation pattern waveforms is transmitted by two-channel electrotactile stimulation. Sound information is represented by using two or three consecutive stimulation patterns. The first pattern is used to notify the fact that a sound occurs. The second pattern is used to notify the direction, and the third one the sound category. In the experiments for stimulation pattern translation for the direction and the sound category, average percentages of correct recognition were 91 and 89%, and the reaction times 1.21 and 1.62 seconds, respectively. It can be expected that the proposed system was useful for practical use indoors.
For future improvements to be widely used the proposed system, it is necessary to shorten operational times for recognizing sound information and the time for transmitting stimulation, and to improve detection ratio of sound information. And it is also necessary to evaluate via experiments for HIP of different ages by constructing the automatic total testing system. Less