Experimental Research of Relationship Between Amplitude Modulation of wind Turbine Noise and its Detection Threshold

풍력 발전기 소음의 부분 변조와 감지 역치 간의 관계에 대한 실험적 연구

Wind turbine noise is known to have special property, very easily detectable and cause annoyance at relatively lower sound level. Previous studies assumed that amplitude modulation might be main factor of the property of wind turbine noise. The studies also said that knowledge of relationship between amplitude modulation and detection threshold can be helpful for reducing the effect of wind turbine noise by using auditory masking. So, the aim of this study is to investigate whether the amplitude modulation is really main cause of high detectability of wind turbine noise or not. And if so, we also wanted to find out how much the detection threshold can be lowered according to a modulation depth. In order to test this, an experiment was conducted using threshold tracking method. Twelve participants determined the detection thresholds of five target sounds in presence of masker sounds. The results showed that detection threshold is lowered as the modulation depth is increased. For reliability, the results were compared with predictions from Glasberg and Moore's model. Modified method of determining detection thresholds is suggested to complement differences between test results and predictions. For effectiveness, the way of determining detection thresholds by using A-weighed maximum sound level is also discussed.