AN EVALUATION METHOD FOR UNPLEASANTNESS DUE TO COMBINED NOISE OF LOW FREQUENCY PURE TONES AND 1/3 OCTAVE BAND NOISE

摘要

An evaluation method for unpleasantness due to combined noise of a low frequency pure tone and 1/3-octave band noise was investigated. A psychophysical experiment was conducted to obtain subjective ratings of 116 stimulus noise conditions on 5-point unpleasantness scale from 12 subjects. The stimulus noise conditions were consisted of 96 combined noise conditions and 20 single noise conditions. The combined noise conditions were mixtures of one of eight pure tones at 5, 10, 20, 40Hz and one of twelve 1/3-octave band noise stimuli with center frequencies of 63, 125, 250, and 500Hz. The obtained subjective rating data were analyzed to estimate optimal frequency-weights for the prediction of unpleasantness of the combined noise stimuli. As the results, it was observed that the best fitted frequency-weights systematically changed depending on the noise levels of the 1/3-octave band noise components of the combined noise. The results were discussed in comparison with the previous experimental results under similar and different stimulus conditions. And a prediction formula of the optimal frequency weights was proposed and the parameters were estimated for the evaluation of unpleasantness of low frequency combined noise at different noise levels.