One challenge engineers face when designing sporty cars is balancing interior noise against the desire to make it sound good. This challenge is extra difficult in the case of hot hatches like the Ford Focus ST. The Blue Oval’s engineers proved their mettle, however, by coming up with a device called an “active sound symposer.”
The symposer is similar to a sound tube that’s been used in the past on cars like the Mustang in the sense that it pumps sound from engine into the interior, but is more advanced. It’s attached directly to the intake manifold and pipes in a specific frequency range – 200 to 450 Hz – into the cabin. The symposer is also fitted with an electronically-controlled valve that opens and closes based on a number of inputs including engine speed, throttle position, and gear selection. The valve is set up to be more aggressive in lower gears and more passive in higher gears for quieter freeway cruising – the best of both worlds.
Thanks in part to the symposer, the Focus ST’s 2.0-liter EcoBoost turbo-four and its 252 hp and 270 lb-ft of torque are going to provide a muscular baritone soundtrack not only for those being passed by the car, but also for the smiling guy or gal behind the wheel. Don’t believe us? Click here to listen to the Focus ST accelerate for yourself.