If you notice more road noise than usual in your Toyota, it is because they decided to go for weight reduction instead of correct NVH sound abatement. They fell for a marketing scheme that says it's better to not block sound from entering the passenger compartment, just absorb it after it gets inside. The material Toyota uses cannot compare to traditional sound treatments that prevent noise from entering the cabin.

Instead of the traditional foam/heavy layer double wall, they use a light weight felt material. If you look above the gas pedal where the carpeting stops, you can see this stuff. It's terrible.

The company that sells the material rigs the testing to show their approach works. In one technical paper, they compare different sound treatments inside the passenger compartment. However, instead of having the road noise come from the outside of the compartment, they use speakers inside the compartment already to emit the road noise. By doing this, they eliminate the advantage of the traditional material that prevents the noise from coming inside in the first place. Their Ultra Light material most likely allows it to pass to the outside of the compartment as easily as it allows it to come inside. Therefore, during their test of loud road noise already inside the passenger compartment, it appears the the Ultra Light is the ticket!

I wonder if the ASL was implemented to correct for too much noise getting into the cabin...

 

What will reduce the noise of the HVAC fan when on high speed. Like when the HVAC is set to AUTO, the car has been sitting in the sun and I start it up. The fan is so loud it's difficult to hear the radio clearly. As the car cools the fan slows down incrementally but for those first minutes the fan noise is quite high.

 

Well, you would think that the Ultra Light would absorb that noise, wouldn't you?

It most likely has to do with the design of the fans. Obviously, noise was not a concern for Toyota.

 

If Toyota found a way to reduce weight (which would improve fuel economy) by switching from heavier materials to its current solution, and the net result is a quiet ride, who would complain?

I hadn't noticed that my TCH was noisy. Everyone who rides in it, including owners of luxury cars, is stunned by the quietness. That doesn't add up to 'scam,' in my opinion, and using the word 'rigged' implies that there was unfairness in the testing.

As long as it's quiet, I don't care how they arrive at the solution. Amen to progress.

 

I second Steve's remarks. Our TCH is one of the quietest cars I've ever driven or ridden in, and that includes many luxury cars and a few true limos.

 

I agree the engine is quiet when in the electric mode.

 

< scratching head >

 

Yea, me too. I'm not sure I understand the concern being raised. Who cares if the sound is deflected, blocked, absorbed, or zapped by energy shields. Whatever prevents the noise from getting to your ear with decent cost and environmental friendliness...

I remember reading some time ago about the Honda Odysee's partial cylinder fuel cut-off technology. Apparently this produced an audible noise into the passenger compartment. Their solution was to use the vehicle's sound system to produce an counteracting sound wave pattern to neutralize the noise. I wonder how much weight that software adds...

 

Ugh!

The problem is that the sound is not blocked, beaten, rubbed out, laserfied, or whatever, before it hits your ears. The sound is let into the cabin where your ears are. Then the sound (which is louder than if it hadn't been allowed to enter the cabin) appears to be louder (because it is.)

Quantifying the numbers, Road & Track quote 62 dBA at 50 mph and 69 dBA at 70 mph. I have measured 67 dBA at 50 mph and 74 dBA at 70 mph for my Camry. These are somewhat higher numbers than luxury cars. (Higher is worse).

I'm sure that Toyota is glad that some of you are enjoying this kind of sound quality.

 

Perhaps your TCH never had those rubber plugs installed during the PDI? They cover holes in the frame used during shipping, I believe. There is a thread here somewhere about them. Some owners reported that they were not installed by the dealer, and found them in the glove compartment or trunk. Installing them quiets the interior. Might be worth a look.

try this: https://www.greenhybrid.com/discuss/...ighlight=plugs