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Sound Deadening Material?

Discussion in 'Gen 4 Prius Audio and Electronics' started by CBarr31, Jan 31, 2016.

  1. Peter the pickle

    Peter the pickle New Member

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    Hey Toyesla,

    I did not do the front wheel wells or liner yet. I'm definitely not finished with the project, and I do plan on tackling that next. A few things that I have been taking into consideration:

    1) I think there's a lot going on under the front fender liner, and not as much surface area of the car body to cover (compared to the back).​

    2)I was thinking about the possibility of applying CCF+MLV to the liner, and not the body. Not sure how effective this would be, but since MLV is a sound barrier, it theoretically should help?
    The trunk modification was certainly effective, with audible results. It also definitely took the least effort. After lining the trunk with CLD, I didn't notice too much of a difference. However, when I topped off the area with CCF+MLF, I got results as described in my other post; road noise sounded "muffled."

    In regard to putting it underneath the floor mats, but above the factory carpet... I've been wondering this myself. I had initially tried it, but I have the factory all-weather mats. They fit really well as it is, so when I added CCF+MLV, it looked pretty awkward. You also will no longer be able to lock down the mat on the driver side. I was thinking since it's over the carpet, it might not need the CCF? Might fit better that way.

    I also feel this tactic still leaves a lot of space exposed, like under the console. Since MLV is most effective with as much coverage as possible, I don't know if this would do much. It could be worth a shot though, I may try this weekend.

    Another thing to note... and this was a recent discovery for me as well: poly-fill??

    I was reading on some honda insight forum that someone stuffed open spaces in his vehicle with poly-fill, and claimed that it produced great results. I have been thinking about this as an option, since I'm not sure what the best approach is to removing the felt liner in the trunk. There is a small gap between the liner and the trunk floor, so it would be possible to stuff the interior side of the rear wheel wells with poly-fill, if that makes sense. I felt around back there, and it seems like Toyota has added this cotton-like material to the back side of the liner. Its the same stuff that's on the inside of the rear door panel cover. Not sure how effective it is at minimizing noise, or what it's actual purpose is for. What are your thoughts on poly-fill?
     
  2. Peter the pickle

    Peter the pickle New Member

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    It's true, sound varies significantly by the road surface. My sound deadening efforts have shown to be effective on most roads except for 880, like in random sections around San Leandro, Oakland, and Berkeley. Anyone living in the Bay area can probably comment on how bad the roads are up that way.

    In regard to tires, I have the Pirelli P7 All Season Plus. Definitely an upgrade in all aspects over the OEM tires. I think they were yokohama bluearths. I've read and heard great things about the Continental TrueContact as well. Not to mention, the touring model has 17 inch rims which will are noisier than 15 inch rims.

    It's been a while since I've ridden in luxury vehicle, but I would think they are still able to maintain a high degree of noise reduction, even over these rough roads at high speeds? Can anyone comment on this?

    Another thing to probably take into consideration is suspension... I think those quiet luxury cars probably have a softer suspension, which would dampen the ride over rough roads. The gen 4 prius has surprisingly good handling, probably due to a stiffer [double wishbone] suspension, so those rough road surfaces affect us more. Does my logic seem correct here? I'm just speculating.
     
    #22 Peter the pickle, May 23, 2017
    Last edited: May 23, 2017
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  3. Toyesla

    Toyesla New Member

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    Re: #2 - You know I was convinced it would help, but if the CCF+MLV isn't on the interior - I wonder how much sense it actually makes to do.

    I haven't looked too much into poly-fill. It looks like it might be a cheap alternative to the standard Sound Deadener Showdown (SDS) approach...but it seems more readily susceptible to moisture issues and also flammability?

    Either way, I ordered 6 linear feet of the CCF & MLV from SDS to try out the trunk application first. With rough measurements, it looked like only 3 linear feet was needed, so I'll use the remainder (assuming no mess ups) to try out under the floor mats.

    I think the sound this car makes is objective, in terms of DBs - and also subjective, in terms of how much does the frequency of noise bother you vs. others. Given that, I got a cheap external mic and plan on getting a Sound Meter app to try to get some numbers on what effect the trunk application makes (in addition to the basic ear test).
     
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  4. Peter the pickle

    Peter the pickle New Member

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    I'm certain you will get results with the trunk application.

    I should have mentioned: I did get a sound meter from amazon (by BAFX products). It doesn't collect an "average" reading, so I just glanced at it often and noted the numbers I saw. I know the readings seem to not add up in respect to each other, but this is all approximation. It was hard to identify which numbers were outliers, so I'm going to just provide a range of what I saw. Generally, the dB readings were consistent in the lower end of the range. I didn't see the high end of the range as much, but enough for me to feel that it should be included. Results, in dB, are as follows:

    Before application
    Course highway roads at 65 MPH: 79 - 84
    "normal" textured highway roads at 65 MPH: 74 - 78
    "smooth" highway roads at 65 MPH: 70 - 74
    Course roads at 40 MPH: 75-79
    "normal" textured roads at 40 MPH: 73-75
    "smooth" roads at 40 MPH: 68 - 73

    After application
    Course highway roads at 65 MPH: 76 - 81
    "normal" textured highway roads at 65 MPH: 69 - 74
    "smooth" highway roads at 65 MPH: 66 - 69
    Course roads at 40 MPH: 71-75
    "normal" textured roads at 40 MPH: 67 - 71
    "smooth" roads at 40 MPH: 63 - 67

    I'm still debating on the poly-fill... Since its synthetic, it technically shouldn't absorb moisture right? I would be applying it to the the interior of the car, so moisture shouldn't be getting in there anyway. Flammability definitely is a concern. Perhaps poly-fill treated with a flame retardant? But how far are we willing to go...

    Good luck with your application!
     
    #24 Peter the pickle, May 24, 2017
    Last edited: May 24, 2017
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  5. Toyesla

    Toyesla New Member

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    Thanks! Are the 'After' numbers based on just the trunk? Or your entire application (doors, etc)
     
  6. Peter the pickle

    Peter the pickle New Member

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    Entire application, including the doors. The drops in dB do seem modest, but a ~4 dB drop seems very audibly significant.

    I did the doors first, and i might have gotten like a ~1 db drop in noise. For the doors, I only applied vibration dampening material (second skin damplifier pro). They do make a satisfying sound when closing though. I haven't applied MLV + CCF to the doors yet, because I don't think I can get it to fit. My door panel wouldn't close the other day, so I'm putting off the project until I can figure out what accommodation I can make. I think its the foam block on the interior of the plastic door cover. The doors are already much heavier as it is, so I don't know if I want to follow through with adding the MLV.

    Attached is a picture of the MLV cutout. I cut slits to feed wires through. I know, it's not the best looking template, but it accommodates for all the holes and wires. I also did the hatch too, in case you were curious about that.

    MLV front door template.jpg
     

    Attached Files:

  7. DonDNH

    DonDNH Senior Member

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    I got a free db meter for my iPhone off the app store - "Decible 10th". It shows average and maximum for a recording session. It could save you a few bucks.
     
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  8. Peter the pickle

    Peter the pickle New Member

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    I'm not sure how accurate sound measuring apps on phones are. Nothing against the app, but I think it is just a limitation of the phone on the loudness it can detect. I could be wrong, but I didn't want to risk it. I think Toyesla said he would be using a sound meter app with an external mic, so we'll see what numbers we get from that. Thanks for the suggestion though!
     
  9. RCO

    RCO Senior Member

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    True they may not be perfectly accurate, but the differential comparisons with will be IMHO.
     
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  10. DonDNH

    DonDNH Senior Member

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    That was my thinking as well. If it isn't accurate both before and after measurements should be off by about the same amount.
     
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  11. Silverprius2

    Silverprius2 Junior Member

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    WOW... 438K miles is amazing! Congratulations!! This gives me so much hope. I love driving and I am glad I don't have to worry about $$ or racking up miles on this car...
     
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  12. CoolPrius

    CoolPrius Active Member

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    Looks great! Compared to my 2013 Prius Persona I find the car substantially quieter. Also, the new suspension and 15 inch wheels really smooth out the ride.