High pitch noise in the front/ over dashboard

What is your question?

There is a high pitch noise/whining came from the front side of my car when I was driving on the highway around 70mph (it also happened before on local way). It lasted a few minutes each time and continued happened for an hour. It won't disappear when I speed up, slow down, turn on/off the AC or even stop. Even I turned off the engine, the noise was still there for 5 to 30 seconds.