[deanr]

http://media.caranddriver.com/files/...april-2012.pdf

BMW 335i (F30) Interior Noise

Idle 42 dBA
Full-throttle 77 dBA
70 mph 69 dBA

Car & Driver, April 2005:

BMW 330i (E90) Interior Noise

Idle 41 dBA
Full-throttle 73 dBA
70 mph 66 dBA

I couldn't find an instrumented test of the E90 335i sedan in back issues of C&D.

Car & Driver:

2007 BMW 335i coupe (E92) Interior Noise

Idle 49 dBA
Full-throttle 75 dBA
70 mph 69 dBA

4-cylinder:

http://media.caranddriver.com/files/...ison-tests.pdf

2012 BMW 328i (F30) (with sunroof) Interior Noise

Idle 40 dBA
Full-throttle 71 dBA
70 mph 66 dBA

http://media.caranddriver.com/files/...2-bmw-528i.pdf

2012 BMW 528i (F10) Interior Noise

Idle 38 dBA
Full-throttle 70 dBA
70 mph 64 dBA

The 2 dBA difference at idle between the current 328i & 335i suggests that differences at speed are due mainly to the louder 6-cylinder engine. The 2 dBA difference at idle between the 328i and 528i must be due to better noise insulation in the 5-series and possibly a noisier exhaust in the 328i.

[lukeb817]

Interesting info.

While a 3dB increase in measured SPL represents a doubling of acoustical energy, what the human ear actually perceives as a difference in "loudness" varies a great deal at different frequencies, the ears/brain don't have a flat response curve. Generally though, the average person needs about a 5+dB change to really notice a difference. I imagine there is also a certain amount of influence on perceived changes in "loudness" resulting from tactile vibrations felt through the seats, floor, or steering wheel. Not sure 2-3dB SPL differences will really be perceptible by most people...at the very least those differences aren't very meaningful without factoring in other variables like frequency and tactile vibrations.

[CoolDude196]

Wow good post, with they'd done the 320d as well... Shame

[PrinceBarin]

Originally Posted by CoolDude196

Wow good post, with they'd done the 320d as well... Shame

I have an SPL meter and a 320d! Will run a test this morning and let you know.

[xit2050]

Originally Posted by PrinceBarin

I have an SPL meter and a 320d! Will run a rest this morning and let you know.

That would be very useful info.

[jpa74]

Originally Posted by lukeb817

Interesting info.

While a 3dB increase in measured SPL represents a doubling of acoustical energy, what the human ear actually perceives as a difference in "loudness" varies a great deal at different frequencies, the ears/brain don't have a flat response curve. Generally though, the average person needs about a 5+dB change to really notice a difference. I imagine there is also a certain amount of influence on perceived changes in "loudness" resulting from tactile vibrations felt through the seats, floor, or steering wheel. Not sure 2-3dB SPL differences will really be perceptible by most people...at the very least those differences aren't very meaningful without factoring in other variables like frequency and tactile vibrations.

Wow! Great explanation.

Interior sound is very subjective indeed. I do enjoy some interior noise. It adds character to the car.

I can't stand hybrids or really quiet interiors (Lexus). I feel like I'm driving a golf cart. They lack "soul".

[jmsent]

Originally Posted by lukeb817

Interesting info.

While a 3dB increase in measured SPL represents a doubling of acoustical energy, what the human ear actually perceives as a difference in "loudness" varies a great deal at different frequencies, the ears/brain don't have a flat response curve. Generally though, the average person needs about a 5+dB change to really notice a difference. I imagine there is also a certain amount of influence on perceived changes in "loudness" resulting from tactile vibrations felt through the seats, floor, or steering wheel. Not sure 2-3dB SPL differences will really be perceptible by most people...at the very least those differences aren't very meaningful without factoring in other variables like frequency and tactile vibrations.

Good explanation. 3dB broadband SPL increase is perceptible, but it isn't a huge difference. Hearing is complex, and it's just as much about what you are hearing as it is how loud the sound is you are hearing. For instance, it's well known that a narrowband high frequency tone of a level far lower than the average broadband noise (wind and road noise) can easily be perceived and be very annoying. That's why things like transmission and differential whine can be such a problem. The actually level is very low compared to the overall noise in the car, but we pick it out and our brains lock onto it.

[Mav555]

Originally Posted by jmsent

Good explanation. 3dB broadband SPL increase is perceptible, but it isn't a huge difference. Hearing is complex, and it's just as much about what you are hearing as it is how loud the sound is you are hearing. For instance, it's well known that a narrowband high frequency tone of a level far lower than the average broadband noise (wind and road noise) can easily be perceived and be very annoying. That's why things like transmission and differential whine can be such a problem. The actually level is very low compared to the overall noise in the car, but we pick it out and our brains lock onto it.

Maybe this is why I feel like the interior isn't as quiet as expected. Although by the data given by the OP, it would seem there wouldn't be too much difference, I perceive the older model was a little quieter. My brain is locking onto the annoying wind noise as I imagine the air buffeting around the windshield/window seals.

[RPM90]

Originally Posted by lukeb817

Interesting info.

While a 3dB increase in measured SPL represents a doubling of acoustical energy, what the human ear actually perceives as a difference in "loudness" varies a great deal at different frequencies, the ears/brain don't have a flat response curve. Generally though, the average person needs about a 5+dB change to really notice a difference. I imagine there is also a certain amount of influence on perceived changes in "loudness" resulting from tactile vibrations felt through the seats, floor, or steering wheel. Not sure 2-3dB SPL differences will really be perceptible by most people...at the very least those differences aren't very meaningful without factoring in other variables like frequency and tactile vibrations.

The measurement in question is "dBa", the "a" makes a difference, which is still the standard for measuring "noise" level. In a car environment, no radio/audio playing, the measurement is being done to test the random noise within the vehicle.

3 dBa is considered "barely noticeable", or more correctly imo, it's a "noticeable" difference, meaning, the average person will be able to tell that there is an increase in volume of that noise.

So, given those numbers in that test, the F30 has a noticeable, louder noise volume when compared to a car with a 3 dBa SPL lower reading.

The E90 tested is a non turbo. The 07 tested is an N54 turbo.
It's interesting that the F30 is louder.
Could be thinner glass to keep weight down.
The tires used can add to this.
Less insulation.

Compare the F30 335i to the F30 328i, it's likely that the same glass and insulation is being used.
Tires may be a part.
But, look at the "full throttle" reading.
328i is 71dBa, and the 335i is 77dBa.
It's likely the engine that's mainly responsible for most, if not all of it.

Interesting catch on this info.
Thanks for posting it.

[RPM90]

Originally Posted by Mav555

Maybe this is why I feel like the interior isn't as quiet as expected. Although by the data given by the OP, it would seem there wouldn't be too much difference, I perceive the older model was a little quieter. My brain is locking onto the annoying wind noise as I imagine the air buffeting around the windshield/window seals.

I haven't noticed as my test drives were limited, and I was paying attention to other things.
Is the wind noise that annoying?
It may not be the volume of it so much as the type of noise it generates.

When you listen to music in the car, do you "forget"/not notice the wind noise?

I tend to drive with the audio on all the time. And if the weather is nice, the window/s are open. It's quite a bit louder then.

[Mav555]

Originally Posted by RPM90

I haven't noticed as my test drives were limited, and I was paying attention to other things.
Is the wind noise that annoying?
It may not be the volume of it so much as the type of noise it generates.

When you listen to music in the car, do you "forget"/not notice the wind noise?

I tend to drive with the audio on all the time. And if the weather is nice, the window/s are open. It's quite a bit louder then.

The noise is not that loud. During my test drive I didn't notice it at all either as I was focused on so many other things. Any kind of music at even moderate levels will drown out any noise from the wind with the windows closed. Overall the cabin is not too loud.

I like to drive with everything turned off sometimes. This is the only time I notice and it gets stuck in my head. Although the F30 has a pretty low drag coefficient, it doesn't seem that the air flows all that smoothly around the seals (or the gutter on the edges of the windshield). I was just surprised at the level of wind buffeting noise, especially at highway speeds @ 70+ (it is not the usual constant wind noise from high speeds).

[Ron Scott]

I will have to suffer...

[RPM90]

Originally Posted by Mav555

The noise is not that loud. During my test drive I didn't notice it at all either as I was focused on so many other things. Any kind of music at even moderate levels will drown out any noise from the wind with the windows closed. Overall the cabin is not too loud.

I like to drive with everything turned off sometimes. This is the only time I notice and it gets stuck in my head. Although the F30 has a pretty low drag coefficient, it doesn't seem that the air flows all that smoothly around the seals (or the gutter on the edges of the windshield). I was just surprised at the level of wind buffeting noise, especially at highway speeds @ 70+ (it is not the usual constant wind noise from high speeds).

Do you sense it coming from the side mirrors?

Modern automobile design and construction has quieted so much of the mechanical sounds we were used to, so that now other sounds seem louder, like little creaks and squeaks which would in older cars probably not be heard over thet engine noise, exhaust, suspension noise, chassis noise and vibration.

I'll have to take more note of it in my next test drives.
My last test drive in a 335i I had the audio off, AC on. I could hear the air coming from the vents. What I wish there was more of is exhaust sound, engine, and intake at greater throttle opening.
But then, this is a "near luxury" car who's design has moved more and more towards luxury sedan than sport sedan.

[bimmerjph]

As long as the difference is due to engine noise I don't see a problem here.

[biologic]

I like to hear my car "roar" when I floor it down.
What I don't like is wind and tyre/road noise
which makes you turn the stereo up.
Particularly wind noise...

[Mav555]

Originally Posted by RPM90

Do you sense it coming from the side mirrors?

Modern automobile design and construction has quieted so much of the mechanical sounds we were used to, so that now other sounds seem louder...
But then, this is a "near luxury"...

I can't really say it is the side mirrors. Although I did notice a lot of wind turbulence around the side mirrors (just looking at how the water droplets get dispersed while driving on the freeways after a car wash, you can see the droplets get tossed around unevenly all over the driver window). I know... It is far from anything scientific but it is as close to a wind tunnel as I'm gonna get.

Anyone notice the piece of plastic that juts out straight off the bottom of the side mirror? It's the continuation of the trim around the mirror. That can't be all too aerodynamic or good for wind noise.

But there is good isolation from road and mechanical sounds. And yes, I would love a bit more exhaust note (not too particular on the 4 w/ direct injection noise) although it is a "near luxury" car. Are our cars classified as "near sport" cars as well?