A Study on the Reproduction of Acoustic Characteristics of a Car's Exhaust Noise Using Digital Filtering Technique

디지탈 필터링 기법(技法)을 이용(利用)한 자동차(自動車) 배기소음(排氣騷音)의 음향특성(音響特性) 재현(再現)에 관(關)한 연구(硏究)

Autoregressive moving average(ARMA) model which is a time domain parametric modeling method is implemented for modeling and reproducing characteristics of exhaust noise of an automobile in various RPM range. Experiments have been carried out using 9 set of exhaust noise signals measured at 1,000-3,000 RPM range. Characteristics of sampled signals were estimated using ARMA modeling and Akaike's FPE(final prediction error) criterion to define exact model structure and for model validation. The digital filter consisted of the esitmated ARMA(70,1) model parameters was programed to reproduce exhaust noise. The spectral analysis of reproduced noise is very close to original. The results show that our approaching technique for reproducing acoustic characteristics is valid and feasible to apply in the field of noise quality control.