# Why the 335d sounds as good as it performs



## Addicted2Torque (Mar 3, 2010)

Intersting article that I got today. I know we all likely agree, but may not have known how much went into making our cars this way

BMW Active Sound Design Takes Diesel Engines to the Next Level 
Futuristic technology matches a passionate driving experience with an intoxicating automotive soundtrack. 


There is no question that an important part of the BMW experience includes the excitement of hearing the engine race through its rpm range while at the same time being insulated from the harsher noises that are sometimes a feature of modern urban or highway landscapes. The type of pleasing audio environment provided by each and every BMW automobile is no accident – rather, it is the end result of millions of dollars and thousands of man-hours spent researching and developing the latest in sound control and sound design technologies.



Nowhere is this supreme effort easier to distinguish than in BMW’s expanding lineup of advanced diesel vehicles. The luxury brand has already invested so much in terms of producing diesel engines, which offer the combination of great fuel efficiency, incredible power and impressively low emissions that it was only natural to turn the attentions of its engineers and designers toward developing the next generation of BMW sound technology to accompany these motors. The goal of the company has been to introduce a sound experience that matches up with a diesel engine’s performance and allows BMW drivers to make the same spiritual connection with these models as they have for decades with the automaker’s gasoline-powered models.



The first challenge undertaken by BMW was to create new and more efficient methods for controlling and reducing vibration. The key to achieving this goal was to shy away from the standard methodologies that simply added thicker levels of insulating material to an automobile, increasing its weight while simultaneously decreasing its performance. Instead, BMW engineers set out on a path which saw them completely redesigning key engine components to feature a new ribbed exterior that is specifically meant to dramatically lower the transmission of any vibration. By addressing noise at the source, it became possible to build diesel engines that are far quieter than those produced by the competition without the need to double or triple the use of traditional insulation materials.



In addition to this breakthrough design concept, BMW also elected to replace parts of its diesel-equipped vehicles with a new structure made of a substance called lightweight reinforced thermoplastic (LWRT). This unique material is not only capable of improving the aerodynamics of an automobile, but it can also act as an insulating material, removing the need to include additional sound deadening during installation. LWRT is lighter and more effective at blocking out sound than past insulators, and since it is an integral part of the subframe itself, it has allowed the undercarriage to become as much as 15 times thinner than those on older, insulation-dependent designs.



The end result of these sound control innovations is a fleet of diesel cars that are as quiet as their gasoline counterparts, whether you are standing beside an idling example or sitting in its passenger compartment. Of course, a peaceful automobile might be relaxing, but it does not exactly evoke the passion that BMW vehicles have historically been known to inject into the blood of enthusiasts, and this takes us to the final piece of the company’s sound management puzzle: Active Sound Design.



Active Sound Design is the term for the technologies used to connect a BMW driver with the most pleasing range of sounds produced by a vehicle while it is being driven. Careful research and experimentation have allowed BMW engineers to install a digital signal processor in each diesel-powered vehicle that not only augments the highlights of the engine’s natural audio characteristics, but that also generates its own special tones, which interact harmoniously with the vehicle’s operation. The processor monitors every aspect of the driving experience in order to appropriately match the sound heard by the driver with the current engine speed and road conditions, maximizing smile-inducing sounds and keeping those behind the wheel completely in tune with every thrilling note the vehicle produces.



Active Sound Design is unquestionably one of the most forward-thinking notions to have ever emerged from the luxury car industry. It is no surprise that it took the enthusiasm of BMW to ask why diesel automobiles could not offer a soundtrack that matched their exceptional performance and acceleration. BMW’s devotion to sound control and sound design is merely one facet of the brand’s refusal to accept the status quo – especially with regards to improving the driving experience of each and every one of its loyal customers.


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## Flyingman (Sep 13, 2009)

Sounds good to me!


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## F32Fleet (Jul 14, 2010)

I've had a couple of non-M BMW's and without a doubt when it comes to getting on the throttle the diesel sounds best.


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## BMW Power (Jul 25, 2007)

So it sounds like they actually add a gasoline sound track to the diesel.

More info: http://www.bmwblog.com/2010/05/24/bmw-active-sound-design/

This is interesting:
Initial research projects have already shown how effective that is. In a MINI prototype presented in 2009, a four-cylinder engine can be made to sound like a powerful V8 engine or superior straight-six engine. Besides the fun factor presented by individualisation, Active Sound Design also has very serious applications, such as helping diesel engines attain even sportier sound characteristics.
An experiment demonstrated what potential this has. The BMW engineers took two identical vehicles and adjusted one of them using sound design such that the sporty qualities of the engine were clearly audible. Subsequent test drives showed that test persons, despite measurably identical longitudinal dynamics, judged the driving performance of the vehicle with integrated Active Sound Design to be better. The subjective in-vehicle impression was comparable to the sensation of an accelerating car with a stronger engine. This means more fun while driving with identical driving behaviour and equivalent fuel consumption.


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## János (Jun 19, 2010)

I'm just imagining what fun it would be if those sound profiles could be customized. You could have anything from this:





To this:





Or we might have something even _more _"dieselish". 













The visuals on that last one were impressive - somebody should send that guy a bottle of DEF!


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## BMW Power (Jul 25, 2007)

János said:


> I'm just imagining what fun it would be if those sound profiles could be customized.


LOL, they could make it a choice in the iDrive like the L7 surrond mode...


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## autoJeff (Oct 1, 2009)

My 2009 335d has a small rubber hose that exits the airbox (I think pre-filter) and terminates in mid air a short distance later. Discussed with the mechanic and he suggests it's there for acoustics. The loose end does point in the general direction of the cabin.

Lately I've been commuting home with the windows open. (it's only around 90 at that hour, after all). Prior to this car I drove manual transmissions almost exclusively. The engine is so smooth and quiet that I find it difficult to feel what gear I'm in. I simply don't hear the engine over wind noise above, say, 45 mph, even around 4k RPMs. Makes me wonder how people drive one around a track in manual mode with windows open. I want to take my D up to VIR but haven't done so yet.


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## KarlB (Nov 21, 2004)

just plug one of these into your power outlet tune in the stereo and viola


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## Stevarino (May 14, 2002)

*Lakes Pipes*

I am thinking about putting "Lakes Pipes" on the 335d so I can get raw engine sound when I need it. Also, to learn some pointers, I am going to watch Steven Spielberg's great movie "Duel" where an unseen diesel truck driver scares the hell out of Dennis Weaver.


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## Flyingman (Sep 13, 2009)

KarlB said:


> just plug one of these into your power outlet tune in the stereo and viola


Hilarious!:supdude:


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## BMW Power (Jul 25, 2007)

flyingman said:


> hilarious!:supdude:


+1!


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## BMW Power (Jul 25, 2007)

Stevarino said:


> I am thinking about putting "Lakes Pipes" on the 335d so I can get raw engine sound when I need it. Also, to learn some pointers, I am going to watch Steven Spielberg's great movie "Duel" where an unseen diesel truck driver scares the hell out of Dennis Weaver.


Do they make Lake Pipes with a DEF port? LOL


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## tlak77 (Aug 5, 2009)

autoJeff said:


> My 2009 335d has a small rubber hose that exits the airbox (I think pre-filter) and terminates in mid air a short distance later. Discussed with the mechanic and he suggests it's there for acoustics. The loose end does point in the general direction of the cabin.


The hose you are referring to point towards turbos, I think it does little more than just a sound...:thumbup:


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