The internal "at rest" sound volume will depend in large part on the external sound level. Do you take the measurement at a construction site, or inside a sound-proofed garage?
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0 is more or less unobtainable. Just the sound of the breeze puts you a decent amount above zero. Remember that 30db is someone whispering 3 feet away.
It's pretty standard to just compare db values without trying to isolate any external noise. Filtering other noises out can get pretty messy. With the cars turned off and stationary, you could perhaps filter it out, but when a car is moving with all sorts of other engine/road/wind noise I suspect it's all but impossible. You're talking about signal processing to remove particular noises to isolate just your car and that's a pretty complicated business. Not to mention when the car is moving the sources of external noise are varying as you travel.
I wonder when we'll see (or why we haven't thus far seen) active noise cancelling in car cabins. Wind and tire noise in EVs is noticeable (again, because there's no loud ICE to mask it) - I would presume with the right mix of microphones and speakers, the car could emit a cancelling sound to reduce overall noise?
2005 Acura RL had active noise canceling (ANC). Worked quite well to remove low frequency engine noise. Did nothing (and didn't try) to eliminate wind noise and tire noise. The ANC used the audio system as a source of the out-of-phase sound signals. It's now available throughout the Acura line.
I believe ANC has moved to Honda's as well.
Interesting - had no idea! I wonder when/if Tesla will add that to the Model S to make the cabin even quieter!
Active Noise Control (ANC) technology (a.k.a., noise-cancellation technology) has severe limitations, and it is not the panacea to solving cabin noise. Here are the criteria for ANC to work:
1. There must be a 2-dimensional plane wave propagating in the space. This happens in HVAC ducts, pipes, vent stacks, etc., and most everything else has 3-D spreading of the sound waves.
2. Due to the short wave lengths in sound energy above 1,000 Hz, (wave length less than 1 foot) ANC does not work for noises with frequency content above approximately 1,000 Hz. In other words, it only works on low-frequency noise, such as that from an internal combustion engine noise. Therefore, wind noise most likely exists above 1,000 Hz, and not a candidate for treating with ANC.
3. The technology works well for low-frequency pure tones, such as that generated by fans rotating in air (blade-passage frequency) and reciprocating ICEs with distinct tonal content, as the ANC system can automatically adjust to variable tones in real-time, sample it, and immediately cancel tones with equal and opposite sound waves (180 degree out of phase). None of this applies to an electric car - no low-frequency pure tones would exist in an electric car, in my opinion.
I know Honda/Acura, and a few other automotive manufacturers, are using ANC, but their ads are misleading, as it isn't really sampling interior cabin noise, but sampling it at the engine, where a 2-D place wave exists. You see inside a car cabin, sound waves spread in a 3-D pattern, which cannot be cancelled, irrespective of what you may hear or read from these auto manufacturers.
Now ANC headphones are a different story, as the volume of space under the earmuff cup is small enough to simulate or create 2-D sound wave propagation.
Now that you are impressed, the bottom line is ANC technology will not work effectively on tire or wind noise audible inside the cabin, mostly due to the 3-D issue I mentioned above. Here the manufacturer (Tesla) is relying upon, and correctly, an air-tight cabin and solid floor and firewall materials; all designed to block and attenuate the penetration of noise. That's it in a nutshell.
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Very helpful. So it sounds like what we get in most EVs of today in terms of wind noise and to an extent, tire noise, will really be the lowest we'll see for some time.
ken830
Model S 85, Model 3 Performance, Model X LongRange
What's missing is a measurement when the car is off. With that measurement, you can then subtract that from each of the other measurements. That would result in the amount of noise on top of the ambient background.
For an EV, the Off and Idle measurements are going to be near identical, confirming your instinctive expectations of no additional noise from the car during "idle". It's also safe to assume, in this case, that the "off" measurement for the Tesla is nearly 35.4 dB.
Note: It's also sorta meaningless to have a "Full Throttle" measurement without specifying a range for the road speed. Unless it's sitting stationary on a pair of rollers, there will be significant road/wind noise.
This seals the deal for me as to how quiet the model is.
Quieter than a soft whisper in a library at a stop light and cruising is like a conversation in a quiet living room.
Quieter than a soft whisper in a library at a stop light and cruising is like a conversation in a quiet living room.
Let's get some clarity here: are we all talking unweighted dB (dBL) with a 20 micropascal reference level?
For purposes of "how loud it sounds", you have to account for the human frequency response curve. So you might use dB(A), or ITU-R 468 noise weighting.
The mere fact that we can consider these questions shows how quiet the car actually is. It's very quiet.
For purposes of "how loud it sounds", you have to account for the human frequency response curve. So you might use dB(A), or ITU-R 468 noise weighting.
The mere fact that we can consider these questions shows how quiet the car actually is. It's very quiet.
SDRick
Active Member
Are there any more interior noise comparison statistics at highway speeds with other cars in the luxury market. My perception is that at speed, the BMW and Mercedes of the world are a bit quieter although I could be wrong.
In my opinion, the most relevant sound reading is the one at freeway cruise. This is the one folks will endure for long periods and tends to be reflected (at lower levels) at other lower steady state cruise speeds. Not surprisingly, wind and tire noise are predominant here which is why my old BMW was quieter than my "electric" Volt (the former was a lot more solid and had a ton of sound deadening despite the big performance tires). You see the same thing for the Tesla, which is, perhaps, why Car And Driver recorded a 70 decibel rating for the Model S while the Lexus LS 460 recorded a remarkably low 66!
It's not all about the drivetrain...especially in high end cars that tend to slather on sound deadening have multiple door seals and even triple-paned side windows, etc.
Tesla: http://media.caranddriver.com/files/2013-tesla-model-complete-specs.pdf
Lexus:http://media.caranddriver.com/files...ar-and-driver2013-lexus-ls460-f-sport-awd.pdf
It's not all about the drivetrain...especially in high end cars that tend to slather on sound deadening have multiple door seals and even triple-paned side windows, etc.
Tesla: http://media.caranddriver.com/files/2013-tesla-model-complete-specs.pdf
Lexus:http://media.caranddriver.com/files...ar-and-driver2013-lexus-ls460-f-sport-awd.pdf
Here is what Consumer Reports said.
"The Tesla is among the quietest cars we've tested; only the Lexus LS was quieter. The powertrain is so silent it's eerie. Even at maximum acceleration, it's drowned out by light wind noise and just a little road noise. Full-throttle noise measurements are the lowest we've ever recorded. The P85D, with its summer-only 21-inch performance tires, transmits more tire noise into the cabin, breaking the calm." I looked on their website but did not find actual sound levels (dB).
"The Tesla is among the quietest cars we've tested; only the Lexus LS was quieter. The powertrain is so silent it's eerie. Even at maximum acceleration, it's drowned out by light wind noise and just a little road noise. Full-throttle noise measurements are the lowest we've ever recorded. The P85D, with its summer-only 21-inch performance tires, transmits more tire noise into the cabin, breaking the calm." I looked on their website but did not find actual sound levels (dB).
SDRick
Active Member
I agree that interior noise at cruising or highway speeds is the most important metric. I took my sound meter today and recorded from 66 to 70 DBA at 80 miles an hour. This is with a glass top and 21 inch wheels. I am debating whether to get the solid top both for sound deadening and ambient light reduction.
Would 19 inch wheels and a solid top result in a quieter cabin?
Would 19 inch wheels and a solid top result in a quieter cabin?
The quietness depends on the tires and the road surface, some tires are quieter than others and some badly interact with certain kinds of road surface and aggregate size. All tires get noisier as they wear, so new tires will be much quieter than the tires you just took off. On my car with 19" tires and pano, if the road surface is smooth, it's very quiet--approaches total silence. On not so smooth roads (like most of the roads around here) not so much, although it's still quieter than the vast majority of ICE cars. On rough roads it's the same as you experience. The other difference is that there isn't the engine vibration. Although you can't hear it, feeling that vibration on a long road trip builds up stress.
It's possible that a solid roof would make some difference, but with all the glass on the car--even with a solid roof--it's not going to be all that noticeable without measuring. I'd guess the sunscreens for the pano and the hatch would make about the same difference (I have them, but I can't really hear any difference, I'd have to measure.
int32_t
Tesla Spotter
Not sure what you're getting at here ... both induction and DC brushless motors are brushless, and the main difference is that the latter has permanent magnets and the former does not. Neither have moving/stationary parts touching stationary/moving parts (i.e., these two types of motors have the same number of moving parts).
I am not sure it would be possible to make an ICE-powered vehicle as quiet as a Tesla if you are trying to go 0-100 in 3.0 seconds ...
int32_t
Tesla Spotter
Background noise is everywhere. For example, photos taken in low light have fuzzy haze in the darker places. This is electrical noise. It is very low-level, but is amplified when the camera tries to eke as much signal out of the sensor as possible in low-light situations. This base noise level cannot be avoided in any system; noise is everywhere. The base level of noise in the Model S could be due to nearby rail traffic, wind, just about anything, really.
SDRick
Active Member
Not sure what you're getting at here ... both induction and DC brushless motors are brushless, and the main difference is that the latter has permanent magnets and the former does not. Neither have moving/stationary parts touching stationary/moving parts (i.e., these two types of motors have the same number of moving parts).
I am not sure it would be possible to make an ICE-powered vehicle as quiet as a Tesla if you are trying to go 0-100 in 3.0 seconds ...
I am sure most around here are very satisfied on how quiet the car is accelerating to speed. Given the quiet characteristics of electric motors some are surprised that interior cabin noise is not as quiet as many ICE cars in this price range.
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