What's the difference between high fidelity and high definition?

What makes a system hi-fi? An audiophile would tell you that a good hi-fi system would reproduce sounds that were identical to the original sound. In other words, a hi-fi system would pick up every nuance of the original performance. It's easier to understand this with an example.

Imagine that you're recording a live performance of a touring symphony orchestra at the Sydney Opera House in Australia. You're using the best audio recording equipment on the market. After the performance, you follow the orchestra to its next destination -- the Lincoln Center in New York City. Again, you record the orchestra's performance with the same equipment.

Later, you decide to listen to the two performances. An audiophile would suggest that you use the best audio systems you could afford to play back the music. That's because the higher-end equipment is usually better at recreating the sound generated from the original performance. On low-end equipment, you might not be able to tell the difference between the two performances. High-end equipment can be another story entirely.

Using the right equipment, you might be able to tell a lot about the original recording conditions. Even if the orchestra was able to perform exactly the same way both times, there would be differences. The acoustics of the two venues wouldn't be the same. Sound would carry in slightly different ways, and this would affect the recording. Some audiophiles say that certain venues imbue recordings with a particular sound or mood, and with hi-fi equipment you can recreate the sensation of actually being at the venue during the performance.

For an audiophile, such considerations are important. The skill and performance of a musician are still critical, but so are many other factors. An audiophile might even claim that he or she could identify the brand of guitar played by a musician based on how it sounds on a hi-fi system.

The ultimate high-fidelity system would recreate sound perfectly. Were you blindfolded, you'd be unable to tell if you were listening to a recording or if a musician were in the room playing right next to you. For some audiophiles, the quest to achieve perfect sound reproduction verges on an obsession.

What about high-definition audio? Is it a meaningful term? Keep reading to find out.

While the term high-fidelity has been around for decades, high-definition audio is a relative newcomer to the scene. The technology company Intel has led the way to defining a set of specifications and hardware for digital sound on computers that they call HD Audio. Unlike hi-fi systems, which can incorporate both analog and digital signals, high-definition audio focuses solely on digital media. It lets your computer act like an audio receiver and amplifier.

The Intel high-definition audio chip allows you to use your computer to send digital audio signals to speakers, headphones, telephones and other audio equipment. Early computer audio systems could only produce simple stereo sound reproduction. The Intel HD audio system supports surround sound up to Dolby 7.1 [source: Intel].

The main focus of the product is to create an immersive experience. Through the use of surround sound, it's possible to create an audio environment in which you're in the center of a performance. That doesn't mean the sound will be an accurate representation of the original recording conditions. Intel's HD Audio system doesn't include outputs like speakers or headphones -- you have to supply those yourself. If you hook up lower end output devices to your computer, the sound you'll hear might not replicate the original performance accurately.

In other words, an inexpensive surround sound theater system might immerse you in the listening experience, but it won't achieve the goal so many audiophiles chase after. But for many home theater applications, such a system would be fine. Even if the system didn't recreate sound to the exacting standards of an audiophile, it could still create an immersive experience as part of a home theater system.

There you have it. A high-fidelity sound system meets subjective standards and reproduces sound accurately. A high-definition audio system supports the latest digital audio formats and creates an immersive experience. The two are related, but aren't interchangeable. It's possible to create a high-fidelity system that doesn't rely on digital media at all, for example. When in doubt, if someone asks you if you'd like to listen to a hi-fi or hi-def sound system, just say "sounds good to me!"

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