Study On The Influence In Sound Transmission Loss By Scale Of The Wall In High Speed Train

Typically, the sizes of materials or components selected in laboratory measurement vary widely due to the limit of the actual conditions, which in many cases does not conform to the requirements in ISO standards or GB standards about sound insulation test in laboratory. Due to the inequality of sound transmission loss among insulators of different sizes, it is clearly that the sound transmission loss in non-standard nor non-real size can hardly evaluates the sound insulation ability of the insulator in actual situation, and the credibility and validity of the measurement in that size should be doubt. Therefore, it must be solved that how the scale of insulator influences the sound transmission loss, by which not only the changing regularity of sound transmission loss affected by scales can be known, the range of scales could be found in which the characteristics of sound transmission loss are equivalent, and the actual measured values get judged in reliability and corrected, but also the sound transmission loss measured in different scales could be predicted and converted to each other, and enhance the flexibility of measuring method and value of measuring result by establishing Insulation-Scale model.It is quite rich in researching the influence of many factors but the scales to the sound transmission loss. Mainly by two ideas of insulation theory about flexural vibrations and radiation theory of modal vibrations, analyzing the sound transmission loss of single homogeneous rectangular panel simply supported on four sides, especially studying the effects of the scale results to the regularity of sound transmission loss according to panel scale, as well as interpretation of its physical significance. Based on the conclusion there gives a method to evaluate and correct the laboratory measurement value of sound transmission loss in different insulator scales. The sound transmission loss of the concrete partition is measured through the reverberation room, which is compared with the calculated values and explained for the effect of its scale. In addition, the feasibility of applying this conclusion to other insulators with doubling, composite and combinatorial structures is also briefly described.With analytic method in this paper, the general rules of impact on sound transmission loss for scale are obtained by studying the scale characteristics of insulators such as area, shape and thickness and analyzing the difference and internal relation of influence between scale and frequency. It is proposed to study the variation of sound transmission loss in different scales through sound radiation efficiency, and presented a method of evaluating and correcting the measurement of sound transmission loss, as while as the feasibility of the conversion and prediction for value of measurements in different scales. With carrying out a sound insulation test in reverberation room, the scale effecting theory above finally gets analyzed and evaluated by comparing the measurements with the calculation.