Helicopter noise from back of car. New rear wheel bearing & brake shoes/drum

I am having the toughest time figuring out what’s wrong with my car. Whenever I go above 30 mph I hear a noise coming from the back of my car that sounds like a helicopter. I have gotten new rear wheel bearings installed, As well as new brake drums & shoes. I do not know what the problem could be. I would like to add that I started to hear this noise after getting new tires put on my car about a year ago. To troubleshoot the tires I went in for a tire rotation. Even after the rotation I still hear the helicopter noise coming from the back of my car. If I only roll down the front windows I hear nothing, but when I roll down only the back windows that is when I hear the noise. My question is what do you think it could be? I also would like to say it has crossed my mind that maybe they didn’t rotate my tires so I am going to try to have them rotated again and this time I’m going to mark my back tires with some type of chalk to see if they’re doing the rotation. 2014 Nissan Sentra Sv, 137,000 miles. New tires. New rear wheel bearings(both sides). New brake drums & shoes(both sides) Good tread condition tires

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Just as an experiment try this. Open the rear windows until you hear the noise. Then partially open a front window. If the noise goes away it is just the airflow into the car. Air can not escape fast enough. I’ve had it happen with both of my Camrys and my Caravan.

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Wind buffeting occurs when you roll down a window while driving, usually at highway speeds. The throbbing, helicopter-like sound is the outside air passing over and interacting with the contained air inside the vehicle. When the two air masses collide, they compress and decompress repeatedly.

My Elantra did it.

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Adding to the above replies, have a passenger watch the headliner and rear package shelf, either could be become loose, rippling in the airflow.

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Ok. I’ll try it later today.

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@It_s-Me is spot on, if this occurs when the back windows are down this is normal and most every car does it. If you have insomnia and want a technical explanation google vortex shedding

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Could be a loose piece of trim or fender liner etc.

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