Tiny whining noise can heard from inside the car

When I am sitting inside my car I can hear a tiny whining noise. It is not my power steering pump because I installed a brand new one with a new pulley last month. My transmission was rebuilt last year in June I had new fluid added. My mechanic notified me that my gasket was not changed as it should have been. So I had been driving the car from June to December before I knew that. I had my transmission fluid serviced yesterday brand new gasket and filter. So my question is, could could this whining noise be related to the transmission or something else? I can only hear it when I’m inside the car and nobody else can hear it but me. It not loud it is very faint.