People don’t just drive sports cars because they want to accelerate quickly and experience the thrill of high speeds – they also want to hear the roar of the engine. And it is exactly that which no longer exists in modern cars. The deep throaty noise, which used to come with high-powered vehicles almost as standard, is these days increasingly disappearing. The reason is the downsizing of the engines, meaning the required performance is achieved with lower displacements. The resounding sporty sound is drowned out, particularly in turbocharged engines, by damping and unwelcome turbocharger noises.
However, resourceful acoustic engineers have been working on solutions for some time. More than a decade ago, our department started developing sound modules capable of recreating the sporty sound we had lost. ‘Symposer‘, ‘Soundpipe‘ and ‘Active Noise Control’ are the names of the sound refiners.
The Symposer works directly at the source. It takes pulsations from the engine close to the throttle body where they have not yet been altered, boosts them and conveys the filtered sound to the driver’s seat, so they can enjoy the sporty sound feedback they love.
A further advantage of this sound transfer is that the vehicle hardly emits any additional noise, as it is known to be the case with sports silencers. Therefore it is easier to comply with legal noise regulations.
The Soundpipe, which was also developed by our company, works in a similar way. However, in this case a vibrating membrane is used as a sound reinforcer, which boosts the pulsations of the engine like a drum. This principle is suitable only for naturally aspirated engines.
Our team at MANN+HUMMEL introduced the world’s first Symposer onto the market in 2005 in the sports version of a compact car. Since then, the innovation has been adopted in a wide variety of vehicle classes, including sports versions of luxury limousines, off-road vehicles, sports coupés and small cars alike. For car manufacturers the small sound modules offer the opportunity to give their sports cars more acoustic drive. In addition, Symposers and similar products also help to fine-tune the engine sound (‘sound design’) or create an engine sound that fits with the brand of car (‘sound branding’).
Sound without Soundpipe
Sound with Soundpipe
As well as passive systems like the Symposer and Soundpipe, active sound generators have also recently started to appear more frequently in cars – one example being Active Noise Control (ANC). With the help of electronics, these devices can generate exactly the required sound. A relatively clean sound is typical of an active sound generator such as ANC, whereas the passive Symposer produces more of a husky ‘dirty sound’. Which one to choose is without doubt a question of taste. Given the increasing availability of hybrid and electric vehicles, it is certain that we will be hearing a lot more about ANC systems in future. They can be used to make electric cars, which run quietly, audible for pedestrians and ensure that the change-over from the electric engine to the internal combustion engine meets consumers’ requirements in terms of acoustics.