Car audio: What's new in digital audio?

What's new in digital audio?

From iPods to radios, the trend in audio is toward digital sound reproduction — and automakers are listening.

A growing number of automakers have responded to the overwhelming popularity of the iPod by introducing so-called iPod integration kits or adapters, which connect the ubiquitous device directly to a vehicle's sound system. Most are simple cables that are hard-wired through the glovebox into the sound system behind the dashboard, but the iPod adapter also can be in the form of a cradle that holds the iPod and uses a built-in FM transmitter to broadcast its contents to the sound system.

With even the least expensive cars sporting a CD player, some luxury automakers are pushing a newer, better-sounding type of digital music disc: the DVD-Audio disc.

Now BMW — the first to introduce an iPod integration kit back in 2004 — is leading auto sound into the newest digital audio realm: HD Radio, a digital broadcasting technology that is gaining popularity among radio stations nationwide. Experts say HD Radio offers sound quality advantages over both traditional radio broadcasts and satellite radio. More automakers are expected to follow in the next few years.

Let's take a closer look at HD Radio, iPod integration kits and DVD-Audio.

Radio goes digital
The newest form of digital audio in automotive applications is HD Radio. The term refers to a new type of radio broadcast transmitted by FM and AM radio stations nationwide, using a "digital carrier" that is combined with the station's analog radio signal — occupying the same radio spectrum. The result is a digital copy of the station's analog broadcast that coexists with it, similar to a color-TV broadcast coexisting with a black-and-white broadcast.

Like an upgrade to a color TV was necessary to see color broadcasts, a new HD Radio receiver is needed to hear HD Radio broadcasts.

Today, BMW is the only automaker offering HD Radio — as a $500 option in the 7 Series, 6 Series and 5 Series. However, it is expected that eight automakers will introduce HD Radio in 40 models during the next several years.

There are 792 radio stations already broadcasting with HD Radio, according to a list compiled by iBiquity Digital Corp. — the company that developed and licenses HD Radio technology — and available at the Web site of the HD Digital Radio Alliance. By the end of this year, says Jeff Jury, chief operating officer of iBiquity, the number of HD Radio broadcasters will climb to 1,200. Jury says 3,000 radio stations have committed to broadcasting HD Radio by 2010. There are approximately 13,000 radio stations in the U.S., according to Jury.

For broadcasters, HD Radio technology can be used to put up to eight radio stations on the air simultaneously, using the same radio spectrum. One or two simultaneous digital channels is considered the practical limit, however, because audio quality diminishes as the number of digital channels increases.

A broadcaster may use HD Radio to air a Spanish-language digital channel in addition to a digital English-language version of its analog channel.

The result is an "explosion of additional content that the consumer can't access unless they have an HD Radio," Jury explains. By the end of this year, approximately 400 radio stations will be broadcasting second or third channels with HD Radio, he says.

Listeners hear audio that is nearly equal to CD quality on FM stations, and perceptibly different from the simultaneous analog broadcasts of both FM and AM stations.

This was unscientifically confirmed with a listening test last week in a 2006 BMW 750i equipped with HD Radio and the optional Premium Sound Package, but the perceived differences between the HD Radio and analog broadcasts seemed to vary with the type of music that was broadcast, appearing more obvious with music that featured lower bass and higher treble tones.

"The quality of HD Radio is not CD quality, but it's close," says Isaac Trefz, a BMW senior product development engineer who worked on the automaker's implementation of HD Radio. Because it is digital, HD Radio is not susceptible to some of the audible problems associated with analog radio broadcasts such as distortion at high volumes and static, noise, hisses or pops from poor reception.

"Realistically, the resolution of the [HD Radio] audio is as good as or better than what satellite [radio] is offering," says Rob Barnicoat, director of business development for Harman/Becker Automotive Systems, which makes the Harman Kardon audio systems offered in BMWs.

"The last major consumer entertainment medium or information medium that's analog is radio," says Jury. Analog radio stations must get on a digital playing field to compete with satellite radio, iPods and even the Internet, he declares.

"iPod Your Car"
Two years ago, the only automaker offering a way to truly integrate an iPod in a vehicle's sound system was BMW. Currently, 16 automakers are marketing iPod integration kits or plan to in the U.S., according to Apple. The company maintains an "iPod Your Car" Web site with links to them all.

Besides BMW, the automakers selling iPod integration now are Acura, Audi, Chrysler, Dodge, Honda, Infiniti, Jeep, Mercedes-Benz, Mini, Nissan, Scion, Suzuki, Volkswagen and Volvo. Ferrari is expected to join the group in the future, Apple says.

Generally, iPod adapters cost between $100 and about $250 depending on the automaker, plus whatever the dealer may charge for installation — and at least one automaker says its iPod adapter is simple enough for the customer to install.

While each of these options will closely tie the iPod to the vehicle, however, there are differences worth noting.

For example, Audi's iPod interface and the original iPod integration kit from BMW — which still is the required adapter for the X3, X5, Z4 and 3 Series coupes and convertibles — doesn't offer access to the song titles, artists' names and other information stored in the device.

But BMW's second-generation iPod integration kit — available in July for the 7 Series, 6 Series, 5 Series and the new 3 Series sedans and sport wagons — does provide that access and more.

Suzuki offers similarly complete iPod integration in the 2006 Aerio — and soon in the 2006 Grand Vitara — as does Honda in the new Fit. Mopar offers an iPod integration kit that fits most Chrysler, Dodge and Jeep vehicles from 1994 and later.

A different kind of disc
In addition to CDs, some automakers also have adopted a different kind of digital audio disc for their sound systems: DVD-Audio.

Acura was the first automaker to include DVD-Audio playability, as a standard feature in the 2004 TL. Today Acura also offers DVD-Audio functionality standard in the RL and, beginning in June, in the new RDX.

Other automakers offering DVD-Audio compatible sound systems include Cadillac, Infiniti, Lexus and Mercedes-Benz.

In January, the 2006 Mercedes-Benz S-Class took auto sound a step further with the introduction of the world's first fully digital car audio system by Harman Kardon — an innovation driven in part by the surround-sound capabilities inherent in a DVD-Audio disc.

The best ears of our lives
What's next? Audi gave a glimpse into the future of auto sound last January at the North American International Auto Show, in its Roadjet Concept. The car, like the upcoming 2007 A8 and S8, featured a Bang & Olufsen sound system with more than 1,000 watts of power and 14 speakers — plus Bluetooth headphones for front and rear passengers.

If we were called upon to draw a conclusion about the next few years of in-car audio technology, it would go something like this: The digital future of automotive audio looks good, and it sounds nearly perfect.

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