| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
From the viewpoint of occupational health, I have interested in frequency analysis on high frequency noise made by dental air turbine handpieces or ultrasonic scalers in dental clinics.In this study, I would like to measure the sound power from these dental equipments, by means of sound intensity measurement.
In the first year, I had purchased a pair of sound intensity measuring devices (microphones) and connected them with a 2-channel FFT analyzer, and I have built a system to measure the sound intensity by using the method of cross spectral analysis. Then, in the laboratory, I gave a continuous sound of which frequency was 5 to 7kHz as mimic sound of dental air turbine handpiece, and illustrated a figure of sound intensity vectors. Through this preliminary experiment, I have found that if a sound source is a point such as dental air turbine handpieces, positioning of the microphones affect the measured value critically. I knew that I would put a greater deal of work in measuring sound
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intensity than I expected ; those are necessity of multi-point measurement, accurate positioning in each grid point, intricate operation of the FFT analyzer severally.
The next year, for making rational experiments, I had prepared a 'grid-point moving board' making use of a drafting board, so that I was able to measure sound intensity vector at any grid point on the board in an area of around 60x60cm. For the purpose of realizing semi automatic measurement, the FFT analyzer was controlled by personal computer through GPIB interface, then it saved time for multi point measurement very well. Results show that sounds of dental air turbine handpieces are scattered not only from the rotary part but also from the grip part of the handpiece analyzed by spectral analysis and sound intensity analysis.
I regret that I should postpone the publication of the result of sound intensity measurement of actual sound on dental equipments which give us high frequency noise, because it was necessary that I spent many days to build up the system mentioned above. The experiments should be continued to attain the desired end. Less
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