Quality evaluation method and quality evaluation apparatus

Abstract

Quality of industrial products is evaluated by evaluating non-stationary operation sound, which is a kind of operation sound, from an aspect of tone, using closely simulated evaluation levels of evaluation of non-stationary sound by used of a human sense of hearing. An operation sound of a conforming product sample is converted into sound waveform data by a sound collecting unit, and the sound waveform data is input into a computer via an A-D converter, and then converted into psychoacoustic parameters. Data of pseudo conforming products is additionally obtained from the psychoacoustic parameters of a plurality of conforming product samples by making use of deviation in the data of the conforming product samples. Threshold data is obtained using thresholds and masking data for evaluation calculated from psychoacoustic parameters of data of the conforming product samples and the pseudo conforming products by a statistical technique. An operation sound of a subject workpiece is converted into sound waveform data by the sound collecting unit, and the sound waveform data is input into the computer via the A-D converter, and then converted into psychoacoustic parameters. Each of the psychoacoustic parameters is compared with the corresponding one of the previously obtained threshold, and thereby the operation sound is evaluated.