Road Noise

i haven't done it, but some with gen 3 have started with the hatch bottom and wheel wells. also, better tires will help, but expensive.

 

I wonder if the ECO type tyres might be contributing? Not sure how you correct that. I would wonder also if the bulk of noise at speed isn't just road noise, but also wind noise. Which sounds odd on a car with excellent aerodynamics. Like all cars, it's built for a purpose as well as a price. To make it as quiet as a Rolls Royce, you'd end up with lots and lots of sound deadening, have to rebuild panels thicker and install thicker glass. All of which would add to the weight substantially.

I'd suggest just drive it the way it is. But if I did want to start with deadening, I'd try putting something like a mattress or a pile of cushions in the boot (trunk/hatch) area and see whether that's the noisiest part - I'd suspect it is.

I don't find PRIUS particularly noisy - it's quieter than my last 3 cars (2006 KIA RIO, 2008 FOCUS Diesel, 2011 FIESTA Diesel) - particularly at rest . And in slow speed city driving, it's superbly quiet.

 

It could also be a relative thing - because I don't hear the sound of a diesel/petrol engine going up and down the gears, I suspect that the next most obvious noises will "be obvious".

A bit like home - when the children go to school, you tend to hear the lawnmower from 2 doors away, the postman's bike in the next street and the traffic noise from 100 metres away - because there is no children chatter and clatter.

Don't try too hard - they tell me that total silence isn't a pleasant experience.

 

I thought my Gen 3 was noisy (17" rims), noisy enough to make me trade it in for a Prius+ (17") which was very quiet, probably due to the 3rd row of seats acting as sound deadening. My gen 4 (17") is somewhere in between, but much quieter than the Gen 3. The quietest Prius in the family is SWMBO's Gen 2 on 16" rims.

 

I think you are spot on starting with the floorboard under the carpet.
Don't forget the firewall.

As for thoughts, wheel wells (dyno inside the removable fender liners) would be second.

I have a v and I notice the roof is thin metal and echos the rain drops from the latest storms we are having in Calif.
This is truly loud.
Dynoing under the headliner could be a good option.

Have fun.

 

In the spring when I make a purchase, my plan is to start in the rear area. It should be a simple task to install Dynamat beneath the carpet. many have written how much quieter the interior is with the luggage curtain closed, so that seems to be where a lot of road noise is coming from.

Dynamat in the doors would be a real chore.

Based on my experience .... I believe the tires are a large part of the problem. In my 2010 Prius, the noise was reduced significantly when I changed from the OEM to Michelin Energy Savers.

 

My early (2012) Uk Prius+ (v) T-spirit had a polycarbonate panoramic roof, which was very quiet.

 

I don't know what kind of cars you guys were driving before the Prius, but I find the Prius to be extremely quiet compared to many cars. Has anybody used a decibel meter to quantify?

I notice more wind noise in the Prius than other cars, but I think it's because the engine and tire noise is a lot quieter than other cars, so you just notice the wind noise more.

 

I used a decibel meter on my VW Jetta and my Prius 4 on the same piece of road and at as close to the same speed as I could using GPS to measure. The VW was ~58 dB and the Prius was ~53 dB. So, it is a pretty minimal difference.

 

it's definitely subjective when you talk about comparison's to other cars, but almost any car can be made quieter. unfortunately, there are side effects to doing so.

 

I believe the original standard for 1 dB was the amount of change barely detectable by the human ear.

 

on a logarithmic scale 6dB is a 50% drop in sound.

 

i don't trust these meters, or more specifically, the method of testing.

 

Felt - please correct me if I am wrong - you do not even own/drive a gen 4 Prius. But you want to modify the (future) car due to road noise?

My 4 touring is very loud over certain road surfaces, and crystal clear silent over new or other pavements I think the Toyota engineers did a great job with soundproofing this car; the floor, roof and pillar assembly, door panels, windows (double pane) and other outside areas. But road road noise rumbles into the cabin over rough pavement, I think through the tires, into the steering column, and the dashboard. I also heard various noises reverberating inside the dash (see my other posts) and sometimes the door panel.

 

Minor correction. It would not be able too travel through the tires into the steering column because they are not connected. The Prius is drive by wire.