Rear windows down - interior noise and air pressure pulsing

Anyone else have a car where if you have the front windows closed and the back windows open on both sides, it really sets up a harmonic pressure pulse at around 50 - 60 mph that shakes the whole interior? I'm wondering if this is a result of the fancy headlights that are supposed to set up an airflow path around the vehicle to minimize noise, but may do so by creating a pair of vortices (little tornadoes) off of the head lights.

It's quite impressive, you can't just let it go it shakes an empty passenger seat back and forth an inch or so!

The effect is called buffeting and occurs on most modern vehicles, especially ones that are designed to be aerodynamic.

My Honda Insight and Leaf both do it very noticeably. I have learned to minimize it by adjusting all 4 sets of windows down by about the same amount. Once you get them right it goes away completely.

-Matt

I noticed this today. It's amazingly powerful! My Murano does this to a lesser extent but only when both front windows are down and the rears are closed. The leaf it's the other way around. But if you open the front windows just a bit, it seems to stop buffeting.

Scared the living crap out of me as I pulled onto the freeway. It really seemed to shake the whole car. Far more powerful that I've noticed on any other vehicle.

My grand cherokee does it bad as well. So weird since if you just crack one front window, it completely goes away..

Oh yes, this is hugely common and I would saying nothing to do with aerodynamics. Every car I've owned that had back windows did this, including my 2000 4Runner. You have a car that doesn't do this?!? I suppose if you had a broken tail window all the air would just flow through... ;-)

The "trick" is just to use a combination of left and right window opening where you don't get the buffeting. Typically opening one window more than the other or partially opening one of the front windows will prevent the buffeting. Not really much of a trick, eh?

If you open the sunroof venting backwards, it goes away, too.

My 2006 Audi A8 does it terribly too...

I was just about to post the same question. If I lower one rear window it's bad - if I lower both, then the pulsing and pressure is quickly overwhelming. Cracking the fronts made it go away but I'm surprised I haven't seen it posted here until now. I've exprienced this before in a few cars, but not even close to the eardrum blowing levels in the LEAF.

The rear windows roll down... I would have never known :roll:

My 2004 Dodge Ram does this terribly if the rear windows are rolled down and front are closed. Feels like its going to blow your eardrums it's so bad, however, my Wife's 2007 Lexus RX-350 barely buffets at all for the front or rear windows.

The phenomena that you are experiencing is called a Helmholtz resonance.

It is exactly the same effect that is the basis for wind instruments like flutes, or an empty bottle. Every car has this issue when air passes over an open window. The way to avoid the sound is to change the natural resonance of the cabin by opening or closing the windows of the car.

OrientExpress said:

The phenomena that you are experiencing is called a Helmholtz resonance.

It is exactly the same effect that is the basis for wind instruments like flutes, or an empty bottle. Every car has this issue when air passes over an open window. The way to avoid the sound is to change the natural resonance of the cabin by opening or closing the windows of the car.

Click to expand...

I just got a weird picture of a "roof flute" where I drill a bunch of holes in the roof and install valves to remote control from the steering wheel, and then play Bach's 3rd Brandenburg...

davewill said:

OrientExpress said:

The phenomena that you are experiencing is called a Helmholtz resonance.

It is exactly the same effect that is the basis for wind instruments like flutes, or an empty bottle. Every car has this issue when air passes over an open window. The way to avoid the sound is to change the natural resonance of the cabin by opening or closing the windows of the car.

Click to expand...

I just got a weird picture of a "roof flute" where I drill a bunch of holes in the roof and install valves to remote control from the steering wheel, and then play Bach's 3rd Brandenburg...

Click to expand...

Now, isn't it AMAZING what you can learn here on this forum? I am overwhelmed, and fighting back tears! :lol: :lol: :lol: :lol: :lol: :lol: