noise reduction

I just purchased a 2012 Prius Two, not II, with 13,000 miles. I had test-driven Priuses before and even rented some for trips several hours long. I knew the ride was stiff, and noticed increased road noise on concrete freeways. However, I didn't realize how noisy and clunky the car would be on very bumpy city streets, esp. concrete. Yes, I did seek out the bumpiest streets around the dealers, but maybe it just didn't sink in--or maybe they weren't concrete. I'm interested in damping the sound, but need to determine what exactly is so noisy. The noises include 1) loud clunking or sharp thwacking on bumps like recessed sewer covers, seams; 2) then there is some low frequency rattling or reverberation related to going over noisy bumps, and then 3) the more superficial-souding rattles that sound like plastic in the interior. The thwacking and the lower pitched, or deeper noises are most bothersome to me since the thwacking is startling, and the deeper rattles seem to reverberate in the cabin and cause fluctuations in air pressure in a subtle way that bothers my ears. I might be totally off, but that is my impression. The superficial plastic rattles are only mildly irritating by comparison.
I'm not a do-it-yourselfer but am interested in ideas for solving the more bothersome sounds; I want to know which sound can be lessened, which can't be, if the design or shape of the interior somehow increases the reverberation of certain frequencies (if anyone knows) --- and how to determine the source of the sounds, if possible.
The road noise from tires doesn't seem to be a problem in comparison to those I described above. I have new tires from dealer. I might try decreasing the air pressure while keeping it within the recommended range, for a slightly softer ride, even though I know this will somewhat affect my gas mileage. Not sure if this would help the thwacking.
I'm happy to try to provide more information or be more specific if that helps anyone. I appreciate input from people who have tackled similar problems. Thanks!

 

Thanks for the tip. I might look into different tires if those become an issue and take note of the ones you recommended. The larger concerns are the hard bumps and related reverberations, not constant road noise, as I associate with tires. Would different tires have any major effect on the noises I described and how the car responds to bumps at low speeds in the city? I just never thought of it.

 

Ha--don't have a Lexus! I can't wear earplugs since I need to be able to hear what is happening around me on the streets, like sirens, etc. and I want to listen to music or the radio, or listen to the person riding with me. Thanks

 

I will check tire pressure and try to reduce it without setting off the tire pressure alert to see what happens. That is an excellent idea. Do you know if shocks or springs are a common solution to Prius complaints? I know that my complaint isn't just isolated to my car. I've read reviews describing the same "thwacking" in Priuses that I've experienced. There is at least one independent hybrid mechanic that I know if in town, now that I think about it ( I just recently brought the car home from the dealer) and he might have some ideas of what's doable and what isn't. Thanks.

 

Yeah--if only I could get paid to investigate why cars are so noisy!
My tires are Bridgestone Ecopia EP20; it says they are "quiet ride" on Bridgestone website. Their "rolling noise" as I will call it, is minimal at freeway speeds on blacktop, but not on concrete, where there is noticeable difference. However, the most bothersome noise is in the city, at low speeds, on bumps. The more I listen as I get used to my car, I believe there is more noise from things rattling than I previously thought, and it's impossible to pinpoint where it's coming from as the driver. I suspect it comes from a variety of places. I've seen posts on damping the doors. I do notice that certain doors sound more hollow that others when I close them.
And by modifying the tire pressure, I can decrease the impact causing reverberation and rattling.
I'll check out the wheel wells out of curiousity. Would be a little sneaky to provide a quieter ride on a 5 (though a different year) since I didn't want a Five for any of the other options. Thanks.

 

I'll ask a hybrid mechanic to see if changing springs is feasible on a Prius. You would think the designers would try to compensate for a rough ride if they could, since it's not an infrequent complaint, so maybe it doesn't work for the design of the car, but what do I know.
Thanks.

 

Thanks for your input, from both of you, My590L and kenniekenken. The doors are tinny, apart from the driver's side, though sometimes they seem noisier and quieter when I close them, randomly. Weird. I'll have my father, who is interested in these things, investigate the wheel wells with me soon and report back. I tend not to know what I'm looking at.

kenniekenken, what product did you use for damping, how did you decide where to "selectively" apply the damping material and most importantly, how easy or hard was it to do, if you did it yourself? I don't want to damage anything by trying to do it myself or not be able to put something back together. I imagined that damping material filled the spaces, such as in doors, to absorb acoustic energy or reduce vibration, perhaps from seeing pictures on websites. However, in your photos, the material appears thinner than I imagined and looks like it maybe just reduces vibration of the material it's attached to. I'm looking at the portions in your photos that looks like tin foil covering a thin square--is that correct? BTW, not all of your pics posted were visible for me, but I saw a couple of doors, and I think the hatch.

Even though the plastic rattling is noisy, and may be contributing to loud thwacks on bumps, it is short-lived. I have to believe that the metallic parts of the car, such as the doors, are what are contributing the other noise source--the bothersome acoustics or reverb and funny air pressure I feel at times. I would like to listen to music at as low a volume as possible to preserve hearing and of course improve the quality of the sound. *Please offer more input into your materials and placement selection, kenniekenken. It sounds like something worth trying. (Tracking down sources of rattling plastic on the other hand, seems impossible and endless right now).
Sorry I don't check in super-frequently, it's not a habit, so please bear with me.

 

Kenniekenken,

I looked at the website for B Quiet and contacted them for some advice. Thanks. What sort of sound level meter do you use? Where did you measure sound--in the front seat where you would be? Or where you thought the noise was coming from just to diagnose the worst noise sources, or both? A 5-6 dB reduction is quite a lot. Sounds promising!