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Quiet Riot: Enhanced Engine Sounds


Today, a huge importance has been put on things being ‘all natural’. This ranges from our food, clothes, soaps, and many things besides. Things that would seem immune from this ‘March of the Natural’ are also falling prey, such as dating partners, athletes, and even our automobiles. Automobiles—a fundamentally unnatural creation—go through periods of development, which change a fundamental character of the car. Before the Second World War, transverse engines and front-wheel drive were going against the grain, unnaturally. After the war, and into the 70’s, the ‘natural’ carburetor gave way to the new electronic fuel injection sweeping the market. Today, some people would want you to believe that the foundations of the automobile are being attacked with such things as fly-by-wire systems, electric cars (although they have an early and long history), and fake engine sounds. The last topic is the newest bone people have to pick with the auto industry, and while some are worth the hate thrown their way, hopefully this explanation of what engine sound enhancers actually are will show that they are not all bad.


This is the question that most people who ‘hate’ sound enhancement systems usually never take the time to answer: why are the automakers bothering with it anyways? While it would be easy to blame environmentalists chocking exhaust systems and engines, and while this is a part of the answer, it is a very, very small part indeed. For the most part, the unstoppable march of technological evolution is to blame, in ways that perfectly demonstrate the odd, unthought-of connections that permeate through any car.

The new Infiniti’s are perfect models for high power (400bhp), swoopy bodies, and small tires with big wheels.

This chain of advancement begins with the most important thing: power. Cars have become increasingly more powerful, to the point that my Fiesta ST makes more horsepower from the factory than a 70’s era big-block muscle car. As power has increased—family sedans often top 400hp these days—certain other technologies must as well. To handle the power, tires have been forced to become wider, while at the same time style dictates that the wheels they are on become bigger, forcing the tires to also become thinner. An unavoidable side-effect of this is the increase in tire-noise which is generated. To ensure that this does not penetrate the cabin, chassis’ have become better built, with significant increases in sound-deadening. This increase in chassis technology is also beneficial in reducing the wind noise often generated by swoopy, safe bodies of todays cars. Not so beneficial is the effect it has on the exciting intake and exhaust sounds that penetrate the cabin: they are no longer there. This connect-the-dot style technological development directly led to the creation of sound enhancing techniques, and seen logically like that, it becomes abundantly clear that some sort of enhancement may be required.

How do they do it?

Automakers go about enhancing their products sound through a number of means. Generally there are three techniques; completely fake engine sounds through a speaker, a mechanical enhancer that uses re-routed air through a device a la kazoo-style, or through direct manipulation of the intake or exhaust systems. The first technique of pumping in pre-recorded audio bites through the car’s stereo system is the one most often looked down upon. For those people that do, I cannot really blame them. This technique, used by cars such as the new Volkswagen Golf GTI and the (much more expensive) BMW M5, is the easiest option to manufacturers, and is the most often used. Often tied-in to the throttle system of a car, they will still ‘rev up’ with the engine, to try and better simulate what would truly be happening with the engine.

The Volkswagen GTI’s engine management screen, showing the sound selection on the bottom.

Often decried as a product of the ‘videogame era’, these systems never get good press, which is a shame because used properly they can work. Already mentioned is the BMW M5, and while a more expensive system would be appreciated, the current speaker-based system does an ok job of providing aural excitement. The best use of such a system is in a car not available on our side of the pond: the Renault Clio 200 R-Spec.

All of the available sound effects can be seen for the Clio R-Spec.

The Clio uses a speaker based enhancement system in the best possible way: as a fun, almost joking, toy. This ‘silly’ air is provided by the amount of selection Renault provides to drivers, allowing not only ‘enhanced’ versions of the car’s engine to be produced through the speakers, but also more exciting offerings such as a Nissan GTR or a Clio Cup car. Allowing the drivers of a small car like the Clio to do something as silly as roar along to the engine of a GTR shows a willingness in Renault to embrace the limits—and benefits—of a speaker based system, forgoing a sense of ‘real’ for a sense of fun.

 The next easiest form of sound enhancement is directly manipulating the already existing flow of gasses in the intake or exhaust system of the car. The best example of this is the Ford Mustang GT.

The Mustang GT’s sound enhancement system circled in red. As seen, it feeds off of the intake system.

The Mustang GT has a ‘resonator’ pipe, which essentially pumps sound from the V8 in the front, through the firewall, due to the effectiveness of the firewall in keeping sound out. There is no device, no amplification, merely a tube pumping sound through to the cabin. This is a good solution—certainly better than fake engine sounds when you have a V8—however it really is as simply as punching a hole in the firewall and is more of a stop-gap solution than a true answer to increased sound deadening.

The Boss 302 of the live-axle, Coyote motor-era of the Mustang goes one step further with its aural enhancement. While also featuring the resonator pipe to the firewall, the exhaust system is sold with a bit of sinus infection.

The side pipes can be seen branching off, to terminate directly ahead of the rear wheels.

 If users wish, they can clear up their exhaust system, and let it breathe, by removing twin blocks installed in the exhaust pipes. Once removed, the twin exhaust pipes in the rear are mostly bypassed, and exhaust gasses are instead funneled to two, de-filtered side pipes on either side of the car. While not the most practical method, it is certainly a very badass way of increasing sound.

The last method used to enhance the soundtrack of a car’s engine is very similar to the Mustang’s resonator pipe, with the addition of a device. The term device is deliberately vague, due to the differences in manufactures techniques, and my inability to truly understand how they work.

The Fiesta ST’s Symposer device in all its drab glory.

Essentially, air is redirected—be it from the intake system, exhaust system, or forced induction system—into a ‘symposer’ type device, which acts like a kazoo, using vibrations to produce sound. This sound is further pumped into the cabin, providing an enhanced engine sound. Such systems are usually used with less-than pleasant sounding direct injected, turbocharged engines. My Fiesta ST has such a system, and my full impressions can be found in last weeks article, here.

Ze Ideal Sound Enhancer

With the three systems in common use today, there is plenty of competition for which is the best on the market. To me, the answer is simple; Porsche.

A very useful graphic from the April 2012 issue of Car and Driver.

 Porsche uses a system very similar to the system in the Fiesta ST, using a ‘kazoo’-type symposer device being fed by a resonator pipe.  The difference that makes it ‘the best’ is simple: the symposer is only fed when in ‘sport’ mode, rather than being all the way on. This means that when you want to quietly cruise along, you can, and when you want a sporty drive, the sound changes accordingly within the cabin. Porsche goes one step further, and amps the sound up again when the car is put into ‘race’ mode, using active valves in the exhaust. This customization—which I wish my Fiesta had—makes the Porsche system the best.

Saying that, it should be said the same advancement that led to the invention of sound enhancing techniques, may very well advance past the need for them. What do you think? Let me know!

Stephen Hyden View All

I recently recieved a degree in History from the University of Nevada, Reno.

4 thoughts on “Quiet Riot: Enhanced Engine Sounds Leave a comment

  1. My 2005 Z4 (e85) has a plastic tube which runs from below the intake manifold through the firewall into the cab. It has two sponge filters embedded into the tube on either end. I removed the sponge filter (about 3.5″ long) on the firewall side. The sound when you accelerate is that of a jet engine — kind of like a sucking vortex. After reaching the desired speed and lifting your right foot the sound goes away replaced by a nice (normal) engine hum. The best of both worlds.


    • I’m not opposed to enhancing sounds, I just wish there was a ‘cut-out’ of sorts, where I could close the symposer tube and get pure engine noise. I think most of the time, if I am forced to choose, I would pick the unaltered sound.


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