Whining noise

MY 05 Envoy has the I6 4 wheel drive with about 85K It has started making and high pitch whine that goes up and down with the rpms. My sisters 05 TB made the same noise and they replaced the alternator, water pump, and the tensioner before the noise quit. Any ideas, I do not want to change out parts to chase it down.

Thanks

MY 05 Envoy has the I6 4 wheel drive with about 85K It has started making and high pitch whine that goes up and down with the rpms. My sisters 05 TB made the same noise and they replaced the alternator, water pump, and the tensioner before the noise quit. Any ideas, I do not want to change out parts to chase it down.

Thanks

Get a listing device like a stereoscope or big long bar or small pipe and see if you can pinpoint noise.
Also pull belt or belts and feel all moving pulleys for noise or slack or rough turning feel.

replace that last part that did they replaced, first, if its "the same noise"