CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [348]
* * *
NOTE As they do with new microprocessor models, Intel gave the HDA standard a codename as well. Look for motherboards offering the Azalia sound option. That’s Intel High Definition Audio.
* * *
NOTE Most chipset makers have adopted Intel High Definition Audio for their better motherboard offerings. That includes direct Intel competitors, such as NVIDIA. Everybody plays Azalia these days!
Processor Capabilities
Sound processor capabilities differ dramatically from the low end to the high end, even though the prices don’t reflect the great divide. The sound processor handles the communication among the application, operating system, and CPU and translates commands into sounds coming out of the speakers. Low-end sound processors do little more than translate, which means that the CPU has to do the heavy lifting on the processing front.
Better sound processors, in contrast, shoulder much of the processing burden and bring a series of extra features to the table. By handling a lot of the processing on board, these better sound processors free up the CPU for other duties and—in effect and in name—accelerate the sound process. These decent sound processors also provide excellent sound reproduction, so your MP3s sound as awesome on your PC as they do on your stereo.
Most mid-range and all high-end sound processors offer support for various surround sound standards, enabling equally equipped games and other applications to provide positional audio effects and detailed sound modeling—features that make PC gaming take on a whole new dimension. You’ll learn about the various standards in detail in the “Speakers” section of this chapter, but for now let an example suffice. With properly implemented positional audio, when you’re sneaking down the hall, ready to steal the Pasha’s treasure, you will hear behind you the sounds of the guards marching up to capture you. Such added realism has many potential benefits beyond games, but games are currently the primary beneficiary of this technology.
Speaker Support
Every sound card supports two speakers or a pair of headphones, but many better sound cards support five or more speakers in discrete channels. These multiple speakers provide surround sound—popular not only for games but also for those who enjoy playing DVDs on their PCs. The card shown in Figure 20-3, for example, has outputs for many speakers.
Figure 20-3 A sound card with multiple speaker connections
Another popular speaker addition is a subwoofer. A subwoofer provides the amazing low-frequency sounds that give an extra dimension to all of your sounds, from the surround sound of a game to the music of a simple stereo MP3 file. Almost all modern sound cards support both surround sound and a subwoofer and advertise this with a nomenclature such as Dolby Digital or DTS. Figure 20-4 shows one type of surround speaker system. (You’ll learn more about surround sound in the upcoming “Speakers” section.)
Recording Quality
Almost every sound card has an input for a powered microphone, but the high-end cards record with substantially lower amounts of noise or other audible artifacts. The measure that describes the relative quality of an input port is signal-to-noise ratio and is expressed in decibels. The smaller the number, the worse the card is for recording, because you’re more likely get noise. Most sound cards at the low end and in the mid range have a signal-to-noise ratio of 30 to 50 decibels, which makes them unacceptable for recording. High-end cards offer a 96 to 100+ signal-to-noise ratio, a level near what professional musicians