Sound generator. What is it actually for?

A

AndyG

Member
Coton in the Elms, South Derbyshire
Hello,
I've owned my 2004 Z4 3.0i convertable for just 2 weeks. This forum and the help of SK93 with the wiper park problem fix has been priceless! Thankyou to everyone concerned with the upkeep of the site and the contributions. Right then, I have tonight removed the bulkhead end foam from my "Sound Generator" with astonishing results. The deep tone produced by this trumpet type thing and delivered into the cockpit is what every chavvy little saxo driver would throttle a granny for. However, I am concerned that I have interfered with an important element of my lovely cars respiratory system. Could anyone please tell me what this system is actually designed for as I cannot believe Germans would have entertained their customers with such a purely hedonistic accessory.
Best Regards, Andy G
 
To quote another forum / post


Early in the development process, BMW began to research what customers prefer as a sporty sound from the car’s engine. Once again a roadster presents unique challenges to the engineers because the acoustics are much different whether the top is up or down.

The process began in the sound lab with people listening to different sound samples. These samples were engine noises but they had been synthetically created on the computer. The goal was to find the ideal roadster sound. This sound shouldn’t be so loud as to disturb one’s neighbors but it should be louder than a luxury sedan. The sound must be “solid” and correspond to what is expected from a BMW. These aspects were all combined and a sound target was designed. This sound target, which is stored as a computer file, was specified in terms of tone and decibel levels. But it also was somewhat subjective.
On the real car, the sources that contribute to the sound the driver and passenger hear include the engine itself, the air intake and the exhaust. The engine noise is very mechanical sounding and while, for example, a Ferrari’s sound is indeed very mechanical; BMW feels that their cars should be more refined.

For the 3.0-liter model only, a special “sound generator” was developed. “Sound generator” is a misnomer; “selective sound filter” would be more accurate. In any case, the sound of the engine is managed in a very specific manner. The sound generator brings the sound back to the firewall to make it more apparent to the driver and passenger. In addition, this system filters out some of the naturally occurring sounds and selects others. The sounds that are selected for are those associated with a performance roadster. The result is a sound, especially upon acceleration, similar to a big V8 engine. Not only is the sound pleasing but it also provides feedback to the driver; the power is heard as well as felt.

In the BMW acoustic labs, the various components can be tested independently. On all three models, 2.2, 2.5 and 3.0 liter, the various sounds are graphed over the whole engine range. The characteristics can be mixed and tuned to complement one another. The process is almost like a musician mixing a recording. Testing is then done in an acoustic chamber with a rolling road. Final testing is, of course, done on actual roads.


PS Welcome to the forum Andy :thumbsup:
 
The basic form of that is, it makes a loud roar in the cockpit while staying quiet outside :)

The only problem i had with my e85 sound generator is that because it's linked to the air intake, the sound can end abruptly which isn't so convincing as a real roar from an exhaust which dies slowly in volume along with associated burbling etc.

It's a nice thought BMW, but I'd rather have had a roar from the exhaust, sod the neighbours ;) lol
 
Hmmm not sure that I'd pay £100 for this mod... If it was just a case of removing the foam then fair enough! Does anyone know if my engine is an N52? I'm struggling to find details on it
 
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