The Research Of The Low-frequency Sound Isolation Technology On Sheet Structure

The rapid development of high-speed railway has brought great convenience to people’s travelling. But the attendant noise problem has increasingly caught our eyes. Traditional acoustic technology works well for the high-frequency. But its performance for low-frequency noise control is not that good as we expected, particularly in the application of the sheet structure. So we need to have a breakthrough based on the traditional acoustic technology. Active sound insulation technology is thus introduced as an innovation which can be a good supplement for the deficiency of the controlling low-frequency noise on traditional acoustic technology.This paper is to study two different active acoustic insulation technologies, including active noise control technology and insulation technology based on mechanical dynamic vibration absorber. For the active noise control technology, first we will analysis its acoustic principle, and then do the system modeling for active noise control technology. Second deriving the algorithm and simulating the entire control system using LabVIEW, then we will analysis the result. As for the insulation technology based on mechanical dynamic vibration absorber, first step is modeling and analyzing the mechanism of vibration damping. After that, we will design, process, assembly the parts of the absorber. Finally test its performance.In order to verify and compare the performance of two active acoustic insulation technology, we will do active acoustic insulation experiments separately on an insulation sheet experimental platform in an anechoic-reverberation chamber. The results showed that both of these two active sound insulation technology can effectively improve the performance of the sound insulation of the sheet structure. Comparing these two active acoustic insulation technology, active noise control technology has higher requirements for controller’s algorithm time step and the control order. Also it’s very fastidious to the sound insulation environment. The size of the enclosed space, physical properties of the secondary source and position of the error sensors have a great impact on the result of control performance. In contrast, insulation technology based on mechanical dynamic vibration absorber is not so sensitive to the noise insulation environment. However, this technology needs good accuracy and decent processing technology of the dynamic vibration absorber. Sound insulation performance is greatly affected by the mechanical structure. At the same time, we need to consider both dynamic/static ratio and space utilization when designing the absorber structure. In the aimed frequency bandwidth of the dynamic vibration absorber, its acoustic insulation performance is better than active noise control technology.