Hasta La Ideas

Earlier I griped about how the act of getting in and out of a car, a very basic automobile experience, is often neglected by designers. With the exception of the Tanto we looked at, there aren’t many examples that demonstrate designers are really thinking about the problem and/or have the clout to address it.

Another lame car-based experience is the helicopter effect, a.k.a. “side window buffeting.” You know the deal—you’re driving at highway speeds when someone in the back cracks their window open, and suddenly your eardrums are assaulted with such a helicopter-rotor-like din that you can practically hear Wagner. Then you must open a window on the other side of the car to try to balance the effect. Or you can do what I do, which is to eject the offending passenger under a strict zero-tolerance policy for disturbing my automotive ecocsystem.

I warned you, dude

Two questions, and the first is: Why does this happen? Jalopnik asked physicist Dr. Stephen Granade to explain:

That “whum whum WHUM WHUM” noise happens because the wind passing over the small window opening… forms tiny tornadoes as it moves past the front edge of that opening. When those tornadoes, or vortices, reach the opening’s back edge, they make a wave of pressure that pushes air into and out of the car. Since sound is nothing more than waves of pressure, this makes noise… The vortices keep pressing on the air in your car just at the right time to make big pressure waves that we can feel and hear.

The technical term for this effect is the Helmholtz resonance, though car people call it “side window buffeting”…

…As you drive faster, the rate at which the whums occur speed up and the loudness goes up.

Interestingly enough, Granade goes on to theorize that “It’s more noticeable in modern cars because they’re more aerodynamic,” the thinking being that cracking a window is more disruptive to a smoothly-tuned airflow. If that’s true, it would mean cars with boxy shapes would suffer less from Hemholtz resonance. Score another plus for the Tanto.

Second question: Why do you think this problem hasn’t been addressed by design? Do you think designers simply don’t have the juice to incorporate a manufacturable solution—or that no one cares?

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