- #3 of 9
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Re: WIND NOISE when rear windows are rolled down [wwest]
by sdc2
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Jul 07, 2008 (11:33 am)
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Replying to: wwest (Jul 03, 2008 5:33 pm)
Yep...it is basically an infrasonic whistle. The RAV does it pretty bad, but I have heard it in many other vehicles as well.
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- #4 of 9
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Re: WIND NOISE when rear windows are rolled down [sdc2]
by tidester HOST
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Jul 07, 2008 (11:50 am)
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Replying to: sdc2 (Jul 07, 2008 11:33 am)
it is basically an infrasonic whistle
If it were infrasonic then you wouldn't hear it.
tidester, host
SUVs and Smart Shopper
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- #5 of 9
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Re: WIND NOISE when rear windows are rolled down [tidester]
by wwest
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Jul 07, 2008 (3:20 pm)
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Replying to: tidester (Jul 07, 2008 11:50 am)
Hmmm...
Then it could be infrasonic....
Do we actually hear it or do we really only feel the air pressure waves...??
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- #6 of 9
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Re: WIND NOISE when rear windows are rolled down [tidester]
by sdc2
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Jul 08, 2008 (5:52 am)
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Replying to: tidester (Jul 07, 2008 11:50 am)
The beat of this effect is less than 10 cycles per second...it is generally assumed that people cannot "hear" sounds below 20 cps and based on my audio experience even this is optimistic. But you can definitely feel it in your head and ribcage. There is a slight bit of noise associated with each beat, I am unsure if these would be considered harmonics, or more likely just produced by turbulence around the window edge (a more perfect whistle would have sharper edges at the opening).
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- #7 of 9
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Re: WIND NOISE when rear windows are rolled down [sdc2]
by tidester HOST
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Jul 08, 2008 (10:14 am)
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Replying to: sdc2 (Jul 08, 2008 5:52 am)
I am unsure if these would be considered harmonics
That would be a good bet. It's quite easy to get a flute to produce harmonics when you up the amplitude a bit. And if the amplitude of the oscillation in the RAV4 is great enough to feel then you're probably above the threshold to produce harmonics.
tidester, host
SUVs and Smart Shopper
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- #8 of 9
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Re: WIND NOISE when rear windows are rolled down [tidester]
by wwest
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Jul 09, 2008 (7:31 am)
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Replying to: tidester (Jul 08, 2008 10:14 am)
But then there is the "vibrations" effect the air pressure waves cause on the interior materials and surfaces.
That might be, predominantly, what we "hear".
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- #9 of 9
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Re: WIND NOISE when rear windows are rolled down [wwest]
by tidester HOST
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Jul 09, 2008 (10:03 am)
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Replying to: wwest (Jul 09, 2008 7:31 am)
Possibly but I don't think we've actually established whether the "sound" is infrasonic and more input from the OP would be helpful. It could just be audible low frequency sound. In any case, it's probably just the ubiquitous "helicopter" effect with sound being produces with pressure changes occurring at the window opening.
tidester, host
SUVs and Smart Shopper
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