Anyone who has opened a car window at highway speeds is likely familiar with wind buffeting – the phenomenon where passengers hear a loud reverberation through the cabin as wind oscillates back and forth. It’s a common occurrence, and can even be slightly uncomfortable. In fact, readers have sent us comments and questions about the phenomenon, describing their experience and asking what’s going on. Now, we’re here to explain what wind buffeting is and why it happens, as well as how to stop it.
GM Authority reader Mark W. recently wrote us asking about buffeting.
“I have a 2015 [Silverado] Duramax, and my wife has a Chevy Equinox, and if you put the back windows down, [the noise] is so bad it hurts your ears,” Mark tells us.
The effect Mark is describing is called Helmholtz resonance, and it’s the result of aerodynamics and a pressure difference between the interior and exterior of the vehicle. Helmholtz resonance requires two basic criteria – a sealed volume with a single opening, and a specific rate at which airflow reaches the surface. In order for a resonance to occur, the rate of airflow entering must match the rate of airflow escaping.
Notably, the more aerodynamically efficient a vehicle design, the more pronounced the Helmholtz resonance will become. Vehicle designs that are not aerodynamically efficient will push the air around the shape, whereas a more aerodynamic design will guide the air around the shape of the vehicle, thus creating a more pronounced pressure difference between the interior and exterior of the vehicle. Indeed, as automakers look for greater and greater aero efficiency as a means of increasing mpg, the effect of Helmholtz resonance in the cabin is likely to increase as well.
Of course, Helmholtz resonance is not unique to GM vehicles, and can be experienced in any car with windows that open. Luckily, fixing the resonance is quite straightforward – simply opening another window will alter the airflow into and out of the cabin, thus disrupting the Helmholtz resonance and making it more comfortable for passengers.
Simple enough. So next time someone brings up buffeting, just mention your pal Helmholtz and reach for the window switch.
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Comments
It is no different than blowing over an open bottle.
Cars today have green houses that are wider in the front and narrow in the back. This is better for sir glow but what gives us the buffeting.
So that is how a whisle functions.
Thought is was a “Cheese Burger in paradise”.
Handle checks out. 🙂
Thanks for explaining nothing other than the Name of the buffeting.
Interesting. An education is a lifelong pursuit.
Also known as an “organ pipe effect”, in this case making a very low bass note.
I never had much use for a center rear window until one morning going to work with my driver side window opened and found that it made it comfortable. A fix for the buffeting problem.
Your colored streams of airflow (above) show why the wing above newer vehicles back windows sucks dust up and deposits it on the rear windows of SUVs. This does not happen on my wingless 2011 Santa Fe. That’s progress??
I agree with Jo. I need to know how to fix it. I have even opened two windows and still have the same problem. Would a window visor deflector rain guard help the situation any?
Since it’s caused by wind entering the cabin I wound think thereis a good chance it would help. I have just never liked the look. I do know from expierence on a pickup, with a sliding rear window, opening the slider stops it.