Hello guys!

 

This is an 07 Outback, 2.5 4EAT.

The car drives perfectly, the transmission shifts great but today, while parking, i opened the door to better see and avoid an object and i noticed a weird and tiny noice come from under the car.In quiet street i did accelerate and i the noise do change rhythm when shift from P to N and to D.

i uploaded a video to Youtube so you can better appreciate.

https://youtu.be/gKqysQKphnE

Have you tried checking the front diff's fluid level?

I didn’t listen but Exhaust heat shields.  Very common in rust prone areas. 
 

if the fluids 14 years old, change it.  highly doubt that will fix your noise but it should be done anyway so I use these opportunities to encourage missed maintenance.