Golf 6 GTD Sound Aktuator stilllegen | Posts 32+

In the Focus ST, it sounds realistically spacious, but many people find it too annoying after the initial excitement wears off. This pneumatic-mechanical solution is susceptible to resonance, and it's particularly loud when the vibrations in the air chamber match the resonant frequency of the membrane, causing it to deflect significantly. Initially, there was likely experimentation with the size and stiffness of the membrane during the pre-production phase. I remember seeing some of the first driveable examples at the AMI in Leipzig, and each one sounded (internally) different. The Focus ST that my friend eventually bought and drove himself sounded different again; it had a much more solid bass response and was tuned to be even lower in frequency. In contrast, the pre-production models in Leipzig didn't offer anything close to such a "powerful" engine sound, were generally quieter inside, and only became truly loud at higher RPMs.

The problem with the exhaust is that, subjectively, it seems even louder in the passenger seat, which would be very annoying for passengers if the noise level is perceived as disturbing. The Focus mentioned above has been retrofitted with sound insulation inside to dampen the noise a bit. However, the owner didn't want to completely change the exhaust system. Since then, you can hear that the engine makes other interesting noises, and even the standard exhaust produces quite lively sounds from the tailpipe. All of this was completely masked before.

Interestingly, with a completely frozen vehicle and therefore also a stiffer membrane, the starting process was as follows: Immediately after starting and lowering the engine speed to its normal level, the sounds it made initially resembled those of a Lanz Bulldog! "Plop! Plop! Plop"