It starts mostly at 59mph (1400rpm) if you accelerate it will stop or if you decelerate it will stop. The sounds continues if you maintain that speed. It has made the noise at 30mph if on an incline. Do you know what is causing the noise? Dealership replaced shift cable it did not fix noise. They are starting a "Report" with GM I will let you know if they find a solution.I think I know what you talking about i might have the same noise sounds liek a some kind ow wine nose and goes away when rpm goes up.