Suppression of Structure-Borne Noise in a Rectangular Enclosure

To date, there is few study on the relation of the structure mode and noise mode as most of researches are only focusing on the modal analysis of the structure-borne noise. This paper presents the extension of study of structure-borne noise analysis in a developed rectangular enclosure which comprises the reduction of structure-borne noise in the enclosure by mitigation method. The suppression of structure-borne noise is significant due to its agonizing effect of causing annoyance and dizziness thus affecting one's life productivity. The vibrational and sound responses acquired from the modal and sound analysis performed on the enclosure using LMS Spectral Testing. Mitigation is executed by placing the stiffeners made up of aluminum sheet metal perpendicularly to the surface of aluminum sheet-metal of the enclosure. The research purpose is to diagnose the relationship between the structural and noise mode that is obtained from acoustic modal experiment. Resonance between the vibration and noise spectrum needs to be avoided to reduce the structure-borne noise in the enclosure. Before the reduction, the frequency from vibration spectrum is 57.8 Hz while from the noise spectrum is 60.3 Hz. It is found that both of the frequencies are close to each other, thus resulting the occurrence of resonance. After the suppression has been made, the frequency from vibration has declined to 38.8 Hz while the frequency from noise spectrum has increased to 72.8 Hz. The large gap between the frequencies from vibration and noise spectrum indicates that the resonance has been avoided. Therefore, the suppression of the structure-borne noise has successfully attained.