Effect of Sound Quality on Fatigue under Long Term Exposure of Noise

摘要

In general, quiet environment is preferred for mental working. However, the realization of this atmosphere may be difficult when the machine generated noise under operation. The purpose of this study was to unveil the effect of sound quality on mental fatigue under long term exposure of noise. For this purpose, two kinds of subjective experiments were made. Subject works visual search tasks for 48 minutes with exposing a test sound, and judges about "Fatigue", "Discomfort", "Powerful", and "Booming" sensations with the 7 category scales in every sixth minutes. In the first test, as its test sound condition 4 kinds of machinery noise and "no-sound" were used. As a result, in cases of "no-sound" condition and "sound D" condition, subjective scores about fatigue are significantly lower than other conditions. In the second test, 8 kinds of test processed sounds based on "sound B" were used. They are weighted differently according to frequency and adjusted in the same loudness(15sone, 11sone) . As a result, on both loudness levels, in case of using test sound under the low frequency decrement, subjective scores about fatigue are significantly lower than others. These results suggested that a direction of sound quality for restraining fatigue will be determined.