The reason: Pakistan's army felt abandoned when the U.S.lost interest in the region following the Soviet withdrawal from Afghanistan in 1989.

VOA: standard.2010.07.08

There's another reason I think these two sound differently and that is the following.

这也是两者听起来的另外一个不同,这是接下来的

耶鲁公开课 - 聆听音乐课程节选