The Effect of Imitation Exhaust Sound on Automobile Audio Enhancements

Few aspects irritate car enthusiasts like artificial exhaust sound. Perhaps my perspective is influenced by my extensive online engagement, but I don’t think I’ve ever met anyone who appreciated engine sounds pumped through their speakers. In addition to feeling artificial, the feature known as Active Sound Design can complicate upgrades for something as straightforward as a subwoofer.

I was unaware of this until I conversed with Ken Ward, the technical marketing manager for Elettromedia SpA. In my view, Ward is an expert in car audio, having developed comprehensive courses to educate dealers and installers on sound production intricacies. He is also a co-founder of Musicar Northwest, a shop renowned for its exceptional work. Ward first highlighted the issues with simulated exhaust noise during a previous discussion, and I reached out to him again for more details.

“The primary point I always start with when discussing this matter is that automakers have three goals for the audio system,” Ward informed me. “The least crucial of those is to ensure listening is enjoyable. This is their least priority.

“Their top priority is utilizing the speakers to transmit non-entertainment sounds.”

Ward clarified that “non-entertainment sound” encompasses a wide range of noises. Whether it’s seatbelt alerts, open-door signals, or hands-free calls, these are the primary concerns for OEMs regarding car audio systems. Artificial exhaust sounds fall into this category, meaning manufacturers prioritize keeping these functions operational over creating a high-quality audio system for music, speech, or other audio.

This is where the aftermarket car audio industry comes into play, but OEMs do not simplify matters. Third-party installers, whether they are high-end audio designers or more conventional specialty shops, need to contend with features such as ASD and ANC, or Active Noise Cancellation. The latter is similar to your favorite over-ear headphones that use microphones to detect surrounding noise and output sound that cancels it out.

Both ASD and ANC utilize a network of microphones to inform a vehicle’s audio system which sounds to produce, whether it’s the throaty roar of a GR Corolla’s turbo three-cylinder or an out-of-phase hum to reduce road noise. They serve distinct functions, but frequently, there’s significant overlap between the two systems. This overlap becomes apparent when an audio installer accesses a car’s wiring and discovers that one minor alteration disrupts a multitude of functions.

“The first-generation Cadillac Escalade was the inaugural Cadillac equipped with embedded noise-canceling microphones,” Ward explained to me. “If a window was down or a door was ajar, the ANC system wouldn’t activate. So when the customer showed up and you pulled the car around, you rolled up the window and closed the doors. Suddenly, [it felt like] a jet taking off inside the cabin of the vehicle.

“Everyone was frustrated since the car was no longer ready, and you had to find a solution. Ultimately, what you needed to do was locate the individual microphones that Bose installed in the headliner. Each of these microphones connected back to the amplifier, and we had to disconnect them. Then everything functioned properly.”

The complexity of ANC systems has only increased since the debut of the early Escalade. Ward shared a recent example with me, a wiring diagram for a Genesis GV80 that has not one, not two, but eight microphones. He described this solved puzzle he assisted a dealer with:

“Those microphones didn’t connect back to the amplifier individually. Generally, microphones connect to a soundboard, and in this instance, the amplifier operates like the soundboard. In the Genesis, each microphone is located on a small circuit board, and that board includes a tiny network chip, and they form a daisy-chain connection with each other. They’re configured in a loop network.

“If you disconnect one microphone, all of them cease functioning. That’s okay in this case, as the only microphones on that network were designated for ANC.”

Others are even more aggravating. Ward pointed out the new Escalade, which repurposes ANC microphones for hands-free calling. You can’t just disconnect these microphones in that scenario, because it would remove safety features. Although Escalade owners can disable some features via a toggle on the infotainment screen, it doesn’t fully resolve the issue, as some microphones still remain in operation.

It’s crucial to emphasize that these challenges are not exclusive to luxury vehicles. Ward also referenced the new Chevrolet Silverado, which comes with a generic, non-Bose audio system. It too features piped-in exhaust sound, and Ward remarked, “I don’t know how to disable it. I don’t know anyone who knows how to turn it off. And that vehicle’s factory audio system lacks bass.” This particular issue is especially frustrating for those who do not intend to retain the original stereo and would likely opt for the non-premium, non-Bose version.

On the ASD side, individual changes can disrupt the entire system as well.

“When we introduce a subwoofer capable of delivering deeper bass at a higher volume without strain, the fake exhaust noise becomes louder and increasingly bothersome,” Ward detailed. “Most exhaust systems exhibit a peak around 50 hertz, which falls within subwoofer frequency range. When a subwoofer capable of 50 hertz is added, suddenly that artificial exhaust note can become overwhelmingly loud and far from subtle.”

In the past, car audio professionals could swiftly tackle these obstacles by disconnecting a wire at the amplifier. Older setups utilized a crankcase position pulse wire corresponding to engine rpm. By not connecting that wire to the amplifier, it couldn’t receive rpm data, and the artificial engine noise would cease.

“In modern vehicles, that wire is no longer available,” Ward explained. “The rpm data is transmitted over the network.”

Ward stated that if he were in charge for a day, he would mandate all car manufacturers to simplify the process of disabling ASD and ANC; a straightforward switch or toggle would suffice. This would save both independent shops and owners considerable time and expense should they choose to enhance their car’s audio system. However, remember: Audio fidelity is at the bottom of the list of priorities for car manufacturers, and this entire article supports that point.

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