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Old 25th January 2013, 17:47   #1
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Default Engine notes, the reality, the future: Sound Enhancement

There’s something very special about the sound an engine makes.

Valves clicking, turbochargers whooshing, pistons thumping. A beautiful melangé of mechanical perfection. Music. A rhythmic, steady, beat. Best accompanied with the silence of an open road.

Romantic almost.


One trend which is catching on, and rather rapidly, is that of artificially enhancing the engine note.

The average car-buyer is incredibly picky. We want a quiet composed cabin that filters all the unruly noise that could potentially intrude our peace. At the same time we rant about how the engine sounds muffled. Or dull.

But if you design a cabin to insulate sound, it will; regardless of whether it is noise or the sweet note of your inline-six. Insulation, unfortunately, cannot differentiate between good or bad sound.

Logical conclusion: use the car’s cracking sound system to play a pre-recorded soundtrack of the engine note. Problem solved. This, essentially, is what the guys at BMW have done on amongst other cars, the new F10 M5.

BMW call this Active Sound Design and explain:

The Active Sound Design technology specially developed for the new BMW M5 takes its cues from the driving situation at any one time to deliver an accurate reproduction of the engine's sound through the car's audio system. The system's digital signal processing exchanges data directly with the engine management, allowing it to reflect the engine's revs and torque, and the car's speed over the road. The result over a smoothly driven journey is a discreet soundtrack in keeping with the harmonious and assured characteristics of the V8 powerplant. A stamp on the accelerator, meanwhile, prompts an immediate audible response to match the instantaneous – and typically M – burst of power from beneath the bonnet.
But what does all this actually mean? A week or so ago, I read an article on Jalopnik in which a person had managed disable the Active Sound Design gadgetry on an M135i.

With Active Sound Design working:

Glorious throaty resonating rumble. It sounds brilliant.

With Active Sound Design switched off:

Raspy. Muffled. Strained.

While this is most definitely not the most scientific method of comparison it is quite evident that Active Sound Design works. And works well.

But at some level it just feels wrong. It feels like, as a car enthusiast, I am being cheated. What if the sound I’m hearing isn’t actually even a pre-recorded version of the same engine?

Yes, it makes sense. Stringent noise pollution levels won’t allow exhaust notes to be loud enough to penetrate through a million layers of insulation, into the cabin, for the enjoyment of the driver. That would be stupid.

It also brings on the benefit of allowing the driver to choose when he or she wants to listen to the engine. Sometimes, when you’re driving back home from work you don’t want to listen to your engine, drone on loudly. Flick a switch, and it becomes quiet. You have a silent cabin at your disposal.

But do I like having this option? I don’t know. (Man, we’re picky.)

Earlier last year, Car and Driver did a piece about how Porsche enhance sound. The Porsche Sound Symposer unlike the BMW Active Sound Design setup doesn’t play a pre-recorded soundtrack. It is an ‘intake noise amplifier’.

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An article on SAE explains:

Electronically synthesized noise is not a Porsche solution, so the engineers developed a new Sound Symposer that is standard on both versions of the car. An acoustic channel picks up intake vibrations between the throttle valve and air filter and a membrane incorporated in the channel reinforces the vibrations and transmits them as an engine sound into the cabin. The system is driver activated or deactivated via a “Sport” button that controls a valve ahead of the membrane.
Is this a better option? Maybe. It certainly appears to be less artificial. I like and respect that.

I guess in the near future all this may not be of much significance at all. With the advent of the electric car these setups would be redundant. Unless of course we get to drive them around with the mesmerizing soundtrack of a rock-solid V8!

What do you guys think? Should we even bother being riled up about this?
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Old 26th January 2013, 13:12   #2
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Default Re: Engine notes, the reality, the future: Sound Enhancement

Thread moved from the Assembly Line (The "Assembly Line" Forum section) to the Technical Section. Thanks for sharing!
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Old 26th January 2013, 14:34   #3
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Default Re: Engine notes, the reality, the future: Sound Enhancement

This is true that sound-full engines enhance our engagement while driving. German car makers always have been fascinated about engine notes and sound. German cars have top of the class sound insulation but why the engine note keep filtering inside the cabin? Because they take the engine sound as a feedback of revving. Drive any silent car for a while and than drive a German car for some time, it will feel more engaging compared to the silent car. But most people end up calling the prominent engine sound as 'noise'.

About future, its true that later we may not see the natural fueled vehicles so obviously the actual engine sound won't be there. Now most manufactures won't mind silent cars but some of them who are obsessed with the engine sound and notes will still keep doing their R&D to achieve the engine rev note.

Maybe we keep seeing the cars with artificial sound in future when the roads will be flooded with electric or hydrogen fuels cars.
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Old 28th January 2013, 13:36   #4
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Default Re: Engine notes, the reality, the future: Sound Enhancement

Here is one more sound comparison. BMW M5 with Active Sound Design enabled and then disabled.

Definitely more subtle here, but it is clear that Active Sound Design fills in with those satisfying, deep, rumbles.
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