low whining noise at low speed, much like a noise of low power steering fluid on 2007 Buick LaCrosse

This noise started about three weeks ago. Since then I have replaced the serpentine belt. The noise got louder and increases with acceleration up to forty miles per hour.As far as I can tell the belt tensioner seems to be OK. The noise is constant.

Asked by for the 2007 Buick LaCrosse
Try listening under the hood with the engine running. Don't get near any moving parts but try to locate the sound. I suspect a failing power steering pump.
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Thanks for the advice, sounds reasonable