I own a 2007 Infiniti G35x and its at 52000KMs. Recently, I have discovered a high pitch ringing sound after i go out for a 5 - 10 minute drive. The sound is really high pitch and can be best heard on the left rear side. The sound isn't super loud but can definitely be heard. Anyone know what it is?

 

any soundclips?

 

I will make one shortly