Charles Brownstein’s annoyance with the “throbbing noise” that invades the cockpit of his Porsche 911 at high speeds became so intense that he turned to an orange juice bottle for relief.  Like millions of car drivers, including those with humbler vehicles, Mr. Brownstein couldn’t handle the oppressive “wub wub wub” head-exploding sensation when certain windows are rolled down. He fixed a makeshift deflector—made of sturdy plastic cut from the side of a Tropicana juice container—to the sports car’s front window frame, which did just enough to divert air from crashing into the cabin.  “I like to solve problems,” said Mr. Brownstein, of Bethesda, Md., noting he has a “working knowledge” of aerodynamics from racing even though he isn’t an engineer.  The vibration actually has a name. It is the Helmholtz resonance, or “wind throb,” and it has long plagued an auto industry that has generally made cars better with each passing year. It is as likely to assail a pricey sports car as it is a compact sedan.  The most common instance of wind throb is when a back seat driver rolls down a window when the front ones aren’t cracked. The usual advice: open a front window. There are other scenarios, too.  Mr. Brownstein and other Porsche drivers complain about the throb happening while traveling at highway speeds or racing down a track. “The noise gets very, very annoying” past 100 miles an hour, Mr. Brownstein said. The 72-year-old stores his homemade plastic “flic” in the glovebox for when he is driving and doesn’t want to pop the sunroof, which also silences the throb.  A Porsche AG POAHY -1.18 % spokesman declined to comment.  Wind throb happens more often now because vehicles are designed to have fewer gaps between parts to eliminate any chance of their cars being labeled rattletraps.  “It is getting worse because cars are getting tighter,” said Stephen Remondi, president of Exa Corp., which designs digital simulation software for auto makers.  The throb is caused by wind passing over flat openings, like a window, in a way that matches the “resonance frequency” of most car cabins. The phenomenon is just like what happens when someone blows over the top of a Coke bottle.  “Most vehicles today, regardless of manufacturer, are sealed so well to improve NVH levels, they can’t vent the volume of air needed to reduce or eliminate the phenomenon,” Jason Nunamaker, a Toyota Motor Corp. TM 1.26 % expert on vehicle frames, said in an email. NVH is an industry term that stands for noise, vibration and harshness.  There are fixes on the market for some of the problems. Some models with sunroofs have a shield that deflects wind on top of the car when the sunroof is opened. Others are selling devices to attach to car window frames. Several U.S. patents have been filed for devices that may eventually adorn new automobiles.  So while the redesigned Honda Civic has been widely praised by auto critics for a suite of enhancements, its occupants may need to fiddle with finding the right window-cracking configurations.  In a highly unscientific test, this reporter found that wind throb made the car’s cabin sound a bit like a European electronic-dance music concert. The pulsing sound barraged the inside of the car and the rearview mirror shook.  Wind throb is “not something that we’re looking into from an engineering standpoint,” said a Honda Motor Co. HMC 0.86 % spokeswoman, because pretty much all cars confront wind throb at moderate to high speeds with a window open, “especially on a highway.”  Those shelling out a few more bucks may find a moment of relief. Jaguar has a solution called the “comfort stop.” The British brand’s “comfort stop” option opens the window just enough to keep the Helmholtz resonance at bay. It can only be overridden if occupants hit the window button again.  Jim Hart, of Grosse Pointe, Mich., has another solution, but it presents some challenges. A few years ago, he rolled down the rear window of his new Buick LaCrosse and mistook the throb for a flat tire. “I called the salesman and said ‘what’s the deal with this?’ ” He says the dealer told him the problem is normal.  Not content with normal, Mr. Hart figured out a homegrown solution: keep the rear seats down, thereby opening a passageway to the trunk.  A General Motors Co. GM 0.23 % spokesman declined to comment.  Inventors working for Ford Motor Co. F -0.08 % have filed for a number of patents that confront the problem. One is an “air extractor,” placed near the rear of the car that is tuned to 12 and 18 Hertz, the usual frequency for wind throb in the cabin, according to patent documents. Another is a “false division bar” that essentially divides the window into two sections to stop wind throb.  “You’re breaking up the strength and you’re breaking up the frequency,” said William Gulker, one of the inventors. He has been working for years on addressing wind noise.  A Ford spokesman, in an email, said “patents are a normal part of our business.” He declined to comment on wind throb.  Eric Franey, of San Diego, Calif., who owns a Porsche, says there is no way to avoid the “excruciating” feeling if you like to compete where he races. Track rules mandate open windows while driving.  He came up with a wind deflector that sticks onto the edge of the door with 3M Co. MMM 0.02 % automotive adhesive that allows owners to attach, detach and reattach at will. His MacGyver’d fix, which he sells for $140 from his website, looks like a triangle that attaches to the trim near the base of the front window.  The device eliminates the “wub wub wub” he says, but “you still hear wind noise.”
From pricey sports cars to compact sedans, drivers confront a common foe: the ‘wub wub wub’ of wind throb.