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I would think Porsche could add noise cancelling software to the 911, and it should be a lot lighter than an insulation package. Hmm, is there an after-market gizmo to add noise canceling to a car?
The problem is proximity inside the cabin. Noise cancellation works by adding the exact same sound as the noise at the precise spot of the observer's ears, but 180° out of phase, so they cancel. Sound is a wave. Noise is a broad spectrum of waves of different lengths (frequencies) from 17 meters long to 1.7 cm long (20Hz to 20kHz).
Road noise is also a wide spectrum, but let's look at the upper frequencies where the wavelength is shorter. At 1,000 Hz you have about 35 cm in wavelength. Half of that wavelength, 17.5 cm, is 180° of phase. So, a 1 kHz signal canceled at one location will be twice as loud as the original signal when you move your head 17.5 cm. The two signals will sum together.
That's just for one occupant. Adding two people will make it impossible to get both in a sweet spot of cancellation for all frequencies. The only reason noise cancelling headphones work is the observer and the headphone are always at the same exact location. However, they are illegal for a driver to wear.
You have a better shot at cancelling the lowest frequencies because the wavelength is so long and Honda has a system that does just that!
I have a 991.1S with PZeros. I find the road noise not especially intrusive for a sports car. I set tire pressure on the Comfort setting. Have taken many long trips in it.
Can you really hear the Burmeister difference at 80 mph?
TOTALLY! The combination of superior output & speaker placement (I’m guessing system processing too) make an immense difference over Bose & base. In fact the differences between the three become more pronounced at speed with more environmental noise to overcome
As an addendum to my previous post - it is highly affected by the road surface itself. Some roads smooth and quiet, others louder and rougher.
This, for sure. Newer, smoother paving is the best, and I can tell without looking when I drive onto older paving with bigger aggregate. And worst of all is concrete with grooves--I hate that s---.
The problem is proximity inside the cabin. Noise cancellation works by adding the exact same sound as the noise at the precise spot of the observer's ears, but 180° out of phase, so they cancel. Sound is a wave. Noise is a broad spectrum of waves of different lengths (frequencies) from 17 meters long to 1.7 cm long (20Hz to 20kHz).
Road noise is also a wide spectrum, but let's look at the upper frequencies where the wavelength is shorter. At 1,000 Hz you have about 35 cm in wavelength. Half of that wavelength, 17.5 cm, is 180° of phase. So, a 1 kHz signal canceled at one location will be twice as loud as the original signal when you move your head 17.5 cm. The two signals will sum together.
That's just for one occupant. Adding two people will make it impossible to get both in a sweet spot of cancellation for all frequencies. The only reason noise cancelling headphones work is the observer and the headphone are always at the same exact location. However, they are illegal for a driver to wear.
You have a better shot at cancelling the lowest frequencies because the wavelength is so long and Honda has a system that does just that!
I have tried the Bose noise-cancelling headphones in my 991.2 and they work pretty well. Just as on an airplane, the headphones themselves cut the noise considerably, and when you turn on the noise cancellation, you get an even stronger effect. I know that they are illegal, but so is my missing front license plate. In fact, I believe that ear plugs are illegal on motorcycles, even though they are essential to prevent hearing loss at highway speeds. Sometimes, common sense has to take precedence over the law. Besides, horn and siren sounds are still audible.
I'm all for giving the consumer choice & people having the freedom to do what they want as long as it doesn't affect others, so upon further reflection it's my opinion that people should stop complaining about how "noisy" the 911 is for the following reasons:
1) It's a sports car, nut a luxo-barge, so by its very nature there needs to be compromise in NVH for performance. I'd hate for Porsche to see feedback like this and be driven to further sanitize the 911.
2) All feedback is good feedback if it's not hindering performance - in an increasingly artificial & digital world we should be savoring all of natural sensory stimulation a far-from-stripped-down sports car like the 911 offers us. I enjoyed hearing the water splash against the underside as I drove to work in the rain this morning.
3) Any engineering effort put towards decreasing NVH would be better spent improving the car - there's plenty of opportunity to make it lighter.
4) If there is sufficient demand for a quieter, more insulated experience, it should be an option package with a price that includes the full NRE so that the more elemental experience of something like the 911 T is the base rather than a special model.
Last edited by fueledbymetal; 05-18-2018 at 09:25 PM.
As I get older, I am less tolerant of harsh riding and noisy cars especially for long road trips. My C4S is much better than the 981 Boxster S that I used to own but I still don’t like long highway drives in it. My wife likes it even less. It is kinda funny. I used to commute 3 hrs a day in the summers in a NB Miata with a Borla exhaust when I was in my thirties. Now, I am not even interested in driving my friend’s modern Miata with the retractable hardtop.
As I get older, I am less tolerant of harsh riding and noisy cars especially for long road trips. My C4S is much better than the 981 Boxster S that I used to own but I still don’t like long highway drives in it. My wife likes it even less. It is kinda funny. I used to commute 3 hrs a day in the summers in a NB Miata with a Borla exhaust when I was in my thirties. Now, I am not even interested in driving my friend’s modern Miata with the retractable hardtop.
I’m a few years away from exiting my 30’s and starting to get there also. When I got my 911 the BMW 128i with the quiet and refined (but much slower) N52 got parked. Few years later now I can’t get the noise out of my head and I find myself reaching for the keys to the Bimmer more often. Life can surprise you sometimes.
I've never thought about replying to this thread but I recently upgraded my floor mats to Coco Mats which have a fairly dense rubber layer on the bottom and there is a noticeable difference in the amount of road noise that you hear/feel coming up from beneath the car. It was not my intention or expectation for this to occur but I don't mind it at all and I would imagine that on longer haul rides as the one mentioned in the OP (FL to VA - which incidentally I may do at some point in the future as we make this trip at least once/year) this may be beneficial. One potential downside to some is the additional weight if that is of any concern being that the Coco Mats weigh close to 15 pounds for the set of 4.
911s have never been too good with road noise. You notice more on newer watercooled cars, the older aircooled made so much racket that wasn't an issue ;-p
The 996 was really bad at this - I thought the 997 a little better. I thought the 991 licked it but no, it was just my new tires... Old P-Zero are awfully loud, old Michelins are a little better but not all that quiet... The first few thousand miles on new tires are golden ;-) It is what it is...
05-17-2018, 01:37 PM
