Auto Tech

Car audio systems: Terms to know, how to listen and what to listen for

Want to option your next car with that fancy, branded premium audio system? Here's how to get peace of mind from your splurging.

Manuel Carrillo III/Roadshow

For music lovers, there has never been a better era in which to buy a new car. Automakers realize your in-car entertainment needs have evolved over the past decade or so, and consequently they're working more closely than ever with speaker companies like Harman and Bose to transform your car into a concert hall on four wheels.

If you're someone who appreciates how music can heighten the driving experience -- or you're wondering if that premium audio system is worth the added cost -- here are the basics to understanding in-car audio.

The 2019 Acura RDX offers a 710-watt, 16-speaker ELS Studio 3D audio system that was tuned by Grammy Award-winning producer and engineer Elliot Scheiner.

Manuel Carrillo III/Roadshow

The audible spectrum: Bass, midrange and treble

Most people are familiar with bass, midrange and treble, the low-, mid- and high-frequency sounds that combine in music. Although commonly recognized terms, it's good to start with these concepts as a refresher, as they provide a platform for understanding the rest of the ideas we'll be discussing moving forward.

The audible spectrum ranges from 20 to 20,000 Hertz. 20 Hz, or 20 cycles per second of a loudspeaker (typically a large subwoofer) moving forward and backward, reproduces the lowest-possible frequency the human ear can perceive. On the flipside, 20,000 Hz means a loudspeaker (typically a small tweeter) is vibrating at a rate of 20,000 oscillations per second. At 20,000 Hz, the human ear is at its upper limit of what it can sense in the high-pitched side of the audible spectrum.

To put that into perspective, bass is any sound that falls between 20 and 250 Hz. Instruments in this range are the tuba (32 Hz), bass drum (100 Hz) and viola (196 Hz). Midrange covers the audible spectrum from 250 to 4,000 Hz, and includes instruments such as the guitar (275 Hz), flute (800 Hz) and piano (2,000 Hz). Finally, any treble sound falls between 4,000 and 20,000 Hz, but musical instruments typically can't surpass 12,000 Hz. A triangle averages 4,500 Hz, while cymbals typically average out to 8,000 Hz.

While it may be tempting to crank the bass and treble, keeping your equalization flat allows you to hear every instrument reproduced as accurately as possible.

Manuel Carrillo III/Roadshow

Keep the equalization flat

Keeping your sound system's equalization (EQ) flat allows you to hear your music in the most accurate way possible. The audio engineers who craft these systems over the entire course of a new car's development tune the vehicle's stereo for flat equalization, based on the audible spectrum.

If an engineer were to tune a sound system for treble-heavy equalization, then you, the consumer, would be forced to focus on the music's high-frequency elements like the cymbals. But that's not how you would enjoy the music if you were at a live performance or in the recording studio. You'd be able to hear the instruments mixed in a way in which every musician complements their fellow performers.

Flat equalization places all of a song's instruments on a level playing field, that way the vocals, bass guitar or crashing cymbals don't overpower the rest of the instruments into the background of their own on-stage or in-studio performance.

Car audio systems offer a couple of different avenues toward adjusting equalization. The most common way is via the bass and treble adjustments. Occasionally, midrange is adjustable, too. Keep those knobs centered at their most neutral (or "zero") setting, and you'll have flat equalization. Sometimes an automaker will get a little fancier and offer you anywhere from a handful to about a dozen control sliders that individually manage the volume of segments within the audible spectrum. Again, leave those sliders alone in their default middle settings, and you'll hear music reproduced in a way that the artist, producer and your premium audio system engineer intended.

Should you fiddle with these adjustments? Sure, but if you're getting acquainted with your new car and its highly engineered premium audio package, it's best to let your ears adjust to the system's natural, flat tuning for a few weeks before you start experimenting with the controls. But, really, you shouldn't need to fiddle with your EQ settings.

Unless you have a passenger from hell who hates music, there's really no reason to adjust your premium audio system's balance and fader settings.

Manuel Carrillo III/Roadshow

Keep the balance and fader centered

"Someone sits in that car for up to a week at a minimum, and they plug into the amplifier and they control each speaker individually in the cabin," says Jonathan Pierce, senior manager of global benchmarking at Harman International. And that's only regarding the tuning phase that occurs close to the vehicle's start of production. Audio suppliers such as Harman have their acoustic engineers present from the beginning of a car's development all the way up to (and sometimes past) the start of production so that the audio system can grow in step with the vehicle.

"They orchestrate this entire thing to come together to be as accurate[-sounding] as it possibly can," Pierce says.

How to listen

Cranking your tunes is great and all, but sometimes it's nice to listen at a softer volume. You should be able to enjoy your premium audio no matter which volume you choose. When testing tunes in your next car, listen at low, medium and high intensities. Notice how well you can hear the various frequencies and instruments across the audible spectrum. Is the bass too subtle at low volumes, but satisfactory when loud? Does the treble start to hurt your ears at a mid-high volume before the rest of the frequencies start to blare?

Ideally, an audio package should have plenty of lows, mids and highs, or have the same balance of frequencies throughout its volume range. When this happens, a system is called "linear." The chart below represents a linear system. Notice how the volume lines look the same? Let that be a visual target for what you're listening for in your next car.

When spectrally analyzed, a good audio system should return consistent-looking lines at various volumes.

Harman Kardon

What to listen for

If you close your eyes, you should be able to "see" where the vocals are coming from. In addition to all the items mentioned previously, if you can quickly pinpoint specific instruments' locations across an imaginary soundstage that seems wider than the car's interior, that's a well setup system.

Sometimes an audio supplier will tune its virtual sound stage to envelop you as though you're on stage with the band. Other suppliers may leave the sound imaging strictly in front of you. Sometimes you're given the option to be immersed on stage or be in the virtual audience, all without having to adjust the fader setting. Either way, you should be able to "see" where specific sounds are emanating. The bottom line is that it should never seem as though you're listening to sound coming from speakers. A great audio system projects the illusion that you're at a live performance.

When listening to your premium audio system, the left, center and right channels should not sound like they're emanating from speakers, but from these virtual orbs instead.

Harman International

How I test audio systems

I have a 10-genre, 21-song playlist ($150 at Crutchfield) in my phone called "Audio System Test." Those are the first 21 songs I enjoy whenever I'm evaluating a new car. It's a good idea to test premium audio with a set of musical selections you know well. The best audio packages allow me to discover instruments I never knew existed in my favorite songs. That's always a pleasant surprise, and it's an easy way for a system to earn extra points in my evaluations.

A personal favorite is the Bentley Bentayga with its optional Naim audio system. I may as well have been in a state-of-the-art recording studio, because I'm able to bring my focus to any instrument as though my fingers are at the helm of an 80-channel, million-dollar mixing console.

But you don't need a $270,000 SUV with a 1,920-watt, 20-speaker array to experience immersive, class-leading sound. Nissan just introduced its $23,000 Kicks with Bose Personal Plus audio, and I'd rank it in my top 10 all-time favorite premium audio systems. It delivers much of the immersive, spine-chilling stimulation and instrumental separation of the Naim system, but with only eight speakers engineered into a vehicle that costs less than one-tenth of the Bentley.

No matter what your budget, there's a transformative audio experience waiting to make your Sunday drive or Monday commute awesome.

More Roadshow guides: