Road Noise

Discussion in 'Gen 4 Prius Main Forum' started by smalltimeart, Feb 24, 2017.

  1. tucatz

    tucatz Active Member

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    OK, well I'm sure owners would agree. We can hear a lot of road noise over certain pavements.

    The engineer in my soul would think that the steering column is connected to the transaxle, connected to the drive shaft, connected to the tires. Let's look at a schematic.
     
  2. bisco

    bisco cookie crumbler

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    same with gen 3. it's all about the pavement.
     
  3. tucatz

    tucatz Active Member

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    That's correct, the decibel scale is logarithic. A 10 dB difference is perceived as twice as loud to the human ear. A 20 dB difference is one hundred times louder, or basically intolerable.
     
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  4. smalltimeart

    smalltimeart New Member

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    My previous cars were all either Volvos, or Audis. Not the sporty ones but more on the "luxury" side. So I guess you could say i'm just spoiled on that side of things. I have had friends in my Prius, and they've all commented on how it does get noisy at higher speeds. I made sure not to say anything so i didn't plant any thoughts in their head.

    I agree it probably has a lot to do with tires and pavement. In this car i can definitely "feel" the road moreso than any other car i've owned. The larger 17" Touring rims and thinner tires transfer more energy to the chassis than say a 15" rim.

    That's a good idea about the Decibel meter. I'm pretty sure i have one kicking around in my garage from my home theater installation days. It'll be fun to get a baseline and then document each change.
     
  5. bbald123

    bbald123 Thermodynamics Law Enforcement

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    Not all sound pressures are equally loud. This is because the human ear does not respond equally to all frequencies: we are much more sensitive to sounds in the frequency range about 1 kHz to 4 kHz (1000 to 4000 vibrations per second) than to very low or high frequency sounds. For this reason, sound meters are usually fitted with a filter whose response to frequency is a bit like that of the human ear. (More about these filters below.) If the "A weighting filter" is used, the sound pressure level is given in units of dB(A) or dBA. Sound pressure level on the dBA scale is easy to measure and is therefore widely used. It is still different from loudness, however, because the filter does not respond in quite the same way as the ear. To determine the loudness of a sound, one needs to consult some curves representing the frequency response of the human ear, given below. (Alternatively, you can measure your own hearing response.)

    From here
     
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  6. royrose

    royrose Senior Member

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    From urbandictionary.com: "Drive-By-Wire," or Electronic Throttle Control (ETC) is a system which severs the direct connection between the accelerator pedal and the throttle control in the engine.

    Smalltimeart: To me, the big question is whether vehicles that transmit much less road/tire noise do so entirely because of sound deadening material or whether they are engineered with more complex linkage that isolates the noise better.

    Our other vehicle, a 9 yr old Nissan Murano, is so much quieter (with no need to turn up the audio on the highway) that I can't believe that it is just due to Dynamat like material.

    Dynamat may help some, I'm just not sure how much. If you try some, I'd love to hear about the results.
     
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  7. kevinwhite

    kevinwhite Active Member

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    The steering isn't drive by wire - there is still a steering column giving a direct connection to the handwheel from the steering rack. The road wheels cannot change steering angle without the handwheel rotating.

    It is Electric Power assisted Steering (EPS) not using hydraulics.

    The only car I know of that has drive by wire capability is the Infiniti Q50 and even that has a clutch to allow direct steering if there is a system failure.

    kevin
     
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  8. Toppcat

    Toppcat Member

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    Toyota s are made cheap... little to no sound insulation! No virbration dampers , Noisy lrr tires.
     
  9. Absolu22

    Absolu22 Junior Member

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    I have no clue what you are talking about! This car is so quiet. :)
     
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  10. Prodigyplace

    Prodigyplace Senior Member

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    Considering they put "Four Touring" in their profile, I agree. I suspect there is less insulation in my trim Two. It is also possible the 17 inch wheels on the Touring tris could add to the noise.
    My trim two is not the quietest car, but I am not sleeping as I drive down the road :eek: :LOL:
     
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  11. kithmo

    kithmo Couch Potato

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    I agree, I think what causes the annoyance is not the sound pressure or dB but the loudness in the human hearing range.
    Soundproofing a car is quite a complicated matter, involving reverberation, reflection and absorption of the various sections and materials in the cabin and panels on the car.
     
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  12. RCO

    RCO Senior Member

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    Agreed, but the accuracy in this case is of secondary importance to the "difference" between two models.

    FWIW, shouldn't the difference be 5dB??
     
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  13. Tideland Prius

    Tideland Prius Moderator of the North
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    That is correct. It's missing the "cowl top panel insulator". It looks like a horizontal plane piece at the base of the windshield (within the engine compartment) based on the diagram.

    upload_2017-2-28_21-15-18.png
     
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  14. tucatz

    tucatz Active Member

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    That's just a flimsy piece of plastic. I opened the hood of my 4 touring and looked at carefully. I doubt it would add much to the noise insulation for the cabin. More important are the interior sound deadening improvements under the car, in the headliner, the double pane windows and exterior wind vortex dongles. IMHO.

    The steering wheel is connected to the wheels. This is where most of the noise on rough pavement enters the cabin.
     
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  15. Prodigyplace

    Prodigyplace Senior Member

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    Your insight on the base level Prime would add an interesting data point though. Especially since you have had long trips.
     
  16. alexgrigori

    alexgrigori Active Member

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    Before go to road noise I need to say that Pruis ICE (4x1.8L) is much louder then my previous Solara (V6x3.3L). With Solara running idle on parking I could barely heard the engine report not only from inside the car but from outside ether. Prius, should ICE engaged, equally noisy inside and outside.
    I think that sound insulation between engine and salon compartments needs much improvements.
    How it may be dome with Dynomat I do not know.
    Look forward to 'hearing' a success stories if any...
     
    #36 alexgrigori, Mar 2, 2017
    Last edited: Mar 2, 2017
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  17. kithmo

    kithmo Couch Potato

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    ICE gets quieter with age, as the engine gets run in and the exhaust gets coated inside.
     
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  18. alexgrigori

    alexgrigori Active Member

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    I forgot to mention that in addition to the noise I feel a vibration that ICE produced especially during warm up on a parking lot.
     
  19. I'mJp

    I'mJp Senior Member

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    Perhaps it's the very quietness of the car in the first place.

    Have you noticed that in the dead of night how the sound of a fly can sound so loud ?
     
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  20. Absolu22

    Absolu22 Junior Member

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    Agreed, and the sound of the air pushed through the vent. Air is so noisy...LMAO
    I often hear other car engines idling around, thinking that my ICE is on, and it's not!
     
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