A time-domain study on the effects of noise source incidence on plenum window with active noise control

Abstract

Active noise control (ANC) applied to the built environment on windows presents itself as a potential solution to reduce noise exposure for residents living near major noise sources since windows are typically the primary path for noise intrusion on a building's facade. The plenum window design seeks to address the dual dichotomy of ventilation and acoustic dilemma that plagues hot-humid and highly noise-polluted cities. In the present study, a time-domain approach is developed to investigate the effect of varying impinging angles of noise sources on the acoustic performance of a plenum window which can represent different storeys of the receiving end of noise exposure. Furthermore, the ANC performance of a control system affected by the varying noise sources is explored in this study. While most ANC studies have limited their scope of study to frequency domain investigations, the present study takes a time-domain approach to account for the causality of the ANC system concerning the primary noise source and secondary control source, which is thus more accurate to the behaviour of a real-time ANC controller. A total of 121 simulation studies were performed, and the findings show that the plenum window's PNC (passive noise control) is affected by the incident angle of a noise source based on its tonal frequency, which is pronounced near the aperture's cut-off frequency, faperture. However, the ANC performance due to varying incident angles of primary noise remains unaffected even at high frequencies with a standard deviation, σANC < 1 dB except for the 630 Hz tonal frequency, which coincides with faperture.