In fact all it is, is a tiny polystyrene bead.

事实上，它就是一个微小的聚苯乙烯珠。

The speaker's create areas of high pressure that can trap a polystyrene bead and suspend it in midair.

扬声器会产生高压区域，可以捕获聚苯乙烯珠并将其悬浮在半空中。