DEVELOPING STUDY ON EVALUATION METHODS OF SOUND INSULATION CHARACTERISTICS OF PLATES USING SMALL AREA MATERIALS AND TRANSFER FUNCTION ANALYSIS

提出了一种非常简单的腭裂隔声特性评价方法。通过这种方法，可以观察到声音通过小面积或在其上存在振动的测试板对入射声音的传递函数的隔声特性。在半自由场中，采用只接收透射声，将衍射声减弱到后面的技术，实现了一种新的方法。因此，不需要专门的声学试验室，如消声室或混响室。不仅可以在正入射条件下进行试验，而且可以在斜入射角条件下进行试验。在建筑物的一个典型房间中，对方形尺寸为900mmx900mm的玻璃板、石膏板和胶合板进行了几次测试，并在其四角边缘进行了支撑，得到了以下结果。首先，通过对比分析结果，可以观察到类似“传递函数”的隔声特性。其次，每种材料或每种入射角的重合效应在高频传递函数中表现为较高的峰值，即声音传输强，较低的峰值，即效果不明显。在不同的入射角条件下，可以清晰地显示出重合效应引起的峰值频率变化。对于两片叶片板壁，采用小型消声室进行隔声试验，降低接收侧板上的直接声压和衍射声压。通过该方法可以观察到低频共振传输效应及其频率随设定条件的变化。该方法在干板墙的设计和开发过程中具有一定的实用价值。

A very simple evaluation method of sound insulation characteristics of a palate was proposed. By this method, sound insulation characteristics could be observed from transfer functions of transmitted sound through a test plate with small area or exited vibration on it against incident sound just to the surface of the plate.A new method could be carried out in semi-free field by using the technique receiving only transmitted sound and reducing diffraction sound to the behind.Therefore, it had not necessity of special acoustical test room such as anechoic room or reverberation room. The tests under not only normal incident condition but also oblique incident angle condition could be carried out. From several tests, in a typical room in a building, on such as glass plate, gypsum board and plywood boards with square size of 900mmx900mm and supported at their four corner edges, following results were obtained.At first, sound insulation characteristics similar "transfer functions" could be observed by comparing the analyzed results. Secondly, coincident effects for each material or for each incident angle were shown as the higher peak, meaning strong sound transmission, and lower peak, meaning not so clear effect, in transfer functions at high frequency range. Also frequency changes of the peak caused by coincidence effect could be clearly shown for each sound incident angle condition.As for two leaf plate walls, using small anechoic chamber was also tested to insulate and to reduce direct and diffraction sound pressures on receiving side plate. By this method, resonance transmission effects in low frequency and their frequency changes with setting conditions could be observed. As the conclusion, the new method is useful in design or developing process of dry board walls.