| 摘要 |
PROBLEM TO BE SOLVED: To evaluate a human sensible noisy degree of a noise caused by a copying machine and a printer as tone quality. SOLUTION: A noise signal obtained by a microphone 1, an analog/digital converter 2 and a data memory 3 is inputted into a feature quantity computing device 4. In a frequency wave form evaluating section 40, a frequency analysis section 41 carrys out the frequency analysis of the noise signal and outputs a frequency wave form to show a relation between the frequency and a sound pressure level, and an acoustic sense compensation computing section 42 compensates an acoustic sense to the frequency wave form, and an approximate wave form computing section 43 carrys out a regression analysis through a quadratic equation to a frequency axis where the frequency wave form is converted into a logarithm and outputs an approximate wave form. A wave form comparison section 44 compares the frequency wave form with the approximate wave form, and a contribution rate computing section 45 obtains the contribution rate of an approximate wave form, and a difference computing section 46 obtains a difference on the comparison result of the wave form comparison section 44. The smoothness of the frequency wave form is made quantitative by the contribution rate and the difference to make the estimation of tone quality possible. |
