Acoustically tuned engine in the new Focus

As well as innovative technology inside the new Ford Focus in Crosby there is a special bit of kit in the engine bay which gives the engines in the 1.6 litre models a better sounding growl under acceleration. The acoustic piece of technology filters out unwanted engine noises, while transmitting pleasing sounds straight inside the car for maximum driver enjoyment.



Although the 1.6 litre EcoBoost engine is very technologically advanced in combining high-pressure direct injection, a low-inertia turbo, plus twin independent variable cam timing, it does have a small downside. The turbocharger inevitably muffles an engine's natural voice, especially higher up the rev range. Flooring the throttle in any turbocharged car and the whoosh of the turbo will overpower the more pleasing engine sound.



The acoustic kit is a small, but hugely effective gadget called a sound symposer to the 1.6-litre EcoBoost engine. The symposer harvests good, engine-generated frequencies from the air intake system and then sends these sound frequencies straight into the passenger compartment.



Ralf Heinrichs who is a Ford Engineer explained, "All engines have their own sound character and it is the exhaust and/or intake system which determines this character. Typically, the exhaust system determines engine sound at low revs whereas higher up the rev range the intake system gives the engine its unique voice."



The symposer itself measures only 60 x 50 x 40mm in size and has four internal chambers - two chambers on the engine side and two on the outlet side. The four chambers are separated by a moveable flap. Under hard acceleration, the pulsations generated in the intake, or engine side, meet the pivoted flap, producing sound waves which are then transferred to the outlet chambers.





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