Prediction On The Coincidence Effect Of Sound Insulation Of Walls

As an important feature of green buildings, good sound insulation becomes an indispensable aspect in the building design. Coincidence effect can reduce the sound insulation performance of walls in certain frequency range, while the mass law can not predict its impact on the sound insulation. So an accurate prediction method should be adopted to predict the impact of the coincidence effect on the sound insulation. On the basis of building materials, structures and economical and practical, statistical energy analysis was used in this paper to found the characteristics and laws of the coincidence effect of walls insulation for exploring appropiate methods to attenuate the coincidence effect.This paper introduces the principle and the impact of coincidence effect of the sound insulation in detail and explains the important concepts on the critical frequency and coincidence valley. And proposed a method to quantitatively describe the depth and width of coincidence valley. This will make the study of the consistent effect more comprehensive, and further expand the sound insulation theory on coincidence effect of walls.Based on the principle of statistical energy analysis, this paper models the single, double panels by SEA, and predicts their sound insulation respectively. The results show that sound insulation frequency curve by SEA can accurately predect the frequency range of coincidence effect and depth of coincidence valley. It is more accurate than the mass law, closer to the measured values and more clearly reflect the characteristics of the coincidence effect.SEA was employed to predict sound insulation of single-leaf wall, which made of commonly used construction materials. The results show that:the sound insulation of all single-leaf walls will be affected by coincidence effect thereby reducing the sound insulation, but how much of the lower value is not the same. Largely reflects that the greater surface density of the component, the smaller affection of coincidence effect and sound insulation reduced. So, coincidence valley will be more shallow. For the same kind of single-leaf homogeneous wall, width of coincidence valley is basically the same regardless of its thickness. But the critical frequency of coincidence effect decreases with the increase of the thickness of the component.On the basis of the sound insulation frequency characteristics of single-leaf wall protected by SEA, two double panels whose thin panel back and towards sound were brought out according to commonly used building materials. And further protected the characteristics and laws of the coincidence effect of this two kinds of double panel. The study shows that double panels whose thin panel towards sound can weaken or even eliminate coincidence valley, especially the depth of the first coincidence valley. And effectively reduce the effects of coincidence effect. Meanwhile, when the thickness of the cavity is about 100mm, the effect of reducing coincidence effect will be more obvious. This paper provides the necessary basis and support for the sound insulation of the building design and wall renovation, and has more important practical value.