Evaluation and Application of Active Noise Cancellation System for Reduction of Traffic Noise

The objective of this study is to evaluate ANC(Active Noise Cancellation) system composed of the prediction model for SPL(Sound Pressure Level) in accordance with the targeted frequencies. The ANC system and prediction model were developed in previous research. Its technical skills were based on ISO 9613. Moreover, we utilized the LimA Predictor to identify the accurate results of traffic noise obtained from measurement and prediction at the receiver points. To measure the traffic noise occurred at the road, the measurement method of Pass-by was conducted. This paper is focused on the reduction and superposition of sound longitudinal wave.: The theory of this paper is based on International Organization for Standardization 9613. In the frequency analysis, we conducted CPB(Constant Percentage Bandwidth) Analysis to determine the traffic noise properties related to the frequencies. In the previous research, FFT(Fast Fourier Transform) Analysis was used to eliminate the engine noise from the friction noise between the road and tire. The LimA Predictor was utilized to simulate the noise propagation and confirm the noise level. Also, the basic wave theory was applied to conduct the reduction of traffic noise from the prediction noise level. The study has shown that the reduction and superposition effect was almost from 11dB(A) to 22dB(A) when the superposition of waves is perfectly applied and the ANC system can be completely compatible with the practical traffic noise. The effect of sound wave reduction using ANC system at the relatively high frequencies was better than the low frequencies. Furthermore the errors of measurement and prediction were small at the range of high frequencies.