Compared to our Toyota Echo, the Prius is silence personified. But the meter provides a way we can objectively measure vehicle noise. However, I need some details to replicate the test methodology:

• speed - what 'air speed' are we shooting for (I assume we're doing level and will adjust for head/side/tail winds)
• distance from door - say 3" or do we want to measure from our shirt pocket? I'm sure we want to keep the instrument isolated from mechanical contact with an vehicle surface.
• delta comparison of closed to open window noise - do we seek the maximum "window noise" or just "open all the way." My experience is about 3-4 inches seems to make a louder racket than all the way down.
• concrete or asphalt - do we need to normalize the road surface? I'm also using 50 psi. What pressure do you use?

We've had folks come here before with a lot of FUD on EMI and electro-magnetic fields. I've always recommended they get a meter and 'do the test.' This gets us out of the mode of arguing opinion and speculations to real facts and data. So you with your meter and I with mine will allow us to do some real compare and contrast measurements. I'm looking forward to comparing the results.

Now my Prius is a 2003, NHW11 model. The body style changed significantly with the 2004 models. However, I have a friend in Huntsville, David Kelly, who is nearly as geekie as I am. He'll love a chance to 'get some data.'

Bob Wilson

 

Freeway speed (65mph). Driver or Passenger seat (dead center in the seat). Windows all the way up. Asphalt freeway.

 

Here is what I found. At 65mph the noise is 68db, not to bad. But at 75mph the noise is 88db, still not to bad. But the issue I discovered is the noise is like a fluttering sound as if there is an air leak. This happens in both front windows and with both cars. I did some checking and was told other Toyota models do this also. A friend with a RAV4 has terrible window noise at freeway speeds. Since this is my first Toyota, it is my first experience with the problem. If this is normal for Toyota, all I can say is, how do you all deal with it? Again I am not impressed with Toyota quality so far. Should I mention the flimsy Prius center console?

 

My '07 Prius touring has similar "problems," except that there is a slight whistling outside the drivers window, at highway speeds, which is amplified when the wind crosses from the RF to LR. Not that annoying mind you, but still worth investigating.

I am wondering if the two are related?

 

A note: For the greatest consistency and meaningfulness of your Sound Level Meter readings, I suggest that you set the averaging time to "long" (the "slow" setting), and use 'A' weighting to approximate the ear's audibility curve.

A possibility: The car is so quiet at speed, compared to normal vehicles (due to the lower engine rpm), that even noises that would be unnoticed in regular cars become audible in these hybrids. So, the real question may be: "Is this noise a sample defect, or just the loudest of the remaining noises?"

Stan

 

I would bet my other bigger engined vehicle works less at freeway speeds and thus makes less noise during this time than my Prius does. The Prius engine simply has to work more at those speeds and thus makes more engine noise then.

 

I would agree with Resist, my other cars were quiet, without the slight whistling that I hear. I am wondering where my noise eminates from, whether it is from the windshield, door seal, or other place. Granted, it is not that bad, nor that annoying, but the car should not be making this nosie.

I previously had horrible wind noise, on my Saab 9-5, and the dealer replaced the door seals three times, before getting it right. This is noise is not as bad as the Saab.

 

Well in my issue, the noise is definately from the side front windows. If I crack them open a tad, I get the same kind of noise at speed.

 

I'll try to pickup the sound meter this weekend. In the meanwhile, you might try moving the side mirrors so they are somewhat parallel to the body instead of sticking somewhat broadside to the slipstream. This may reduce the velocity between the mirror and the car body and make a change. . . . just a suggestion.

The mirrors are designed to slip out of detent if a clumsy person or poor driver comes too close. This would be just a temporary test.

Bob Wilson

 

The side mirrors have nothing to do with it. Air is leaking in, it is that plain and simple. Personally I wouldn't waste your money on a sound level meter. I am thinking about taking mine back. It won't measure anything under 50db. It can't even pick up the sound I hear from my computer, unless I place it right up to it. The sound I heard in my Prius was easily heard with my ears, I can even tell what part of the window seal it is leaking in from with my ears.