Using 3D Audio

One of the biggest issues for serious game players when audio adapters are considered is how well they perform 3D audio tasks. This has been complicated by several factors, including the following:

  • Differing standards for positional audio

  • Hardware versus software processing of 3D audio

  • DirectX support issues

Positional Audio

The underlying issue common to all 3D sound cards is that of positional audio, which refers to adjusting features such as reverberation; balance; and apparent sound "location" to produce the illusion of sound coming from in front of, beside, or even behind the user.

One very important element in positional audio is HRTF (Head Related Transfer Function), which refers to how the shape of the ear and the angle of the listener's head changes the perception of sound.

Because HRTF factors mean that a "realistic" sound at one listener's head angle might sound artificial when the listener turns to one side or the other, the addition of multiple speakers that "surround" the user, as well as sophisticated sound algorithms that add controlled reverberation to the mix, are making computer-based sound more and more realistic.

The technology might be promising, but one of the most frustrating problems for PC game players in particular has been the continued rivalry between various APIs designed to perform essentially the same task, such as the battle between the now-defunct 3dfx Glide standard and OpenGL for graphics, or the battle over which 3D audio standard to support.

The original version of Microsoft's Direct3D for DirectX didn't support third-party 3D software, but recent and current versions do, enabling 3D audio adapters to improve the normal positional audio available with Direct3D.

During 1999 and the first part of 2000, the major rivals for the most popular gaming 3D standard were Aureal's A3D and Creative Labs' EAX (Environmental Audio Extensions) technology. A3D, especially in version 2.0, was frequently regarded as superior to its Creative Labs rival.

However, most developer support went to EAX. When Aureal closed in mid-2000 and was later absorbed by Creative, this spelled the end for A3D as a viable game API. Virtually all new sound cards on the market support Creative's EAX, while Creative's own Audigy and Audigy 2 series has gone onto the next level with EAX Advanced HD, which supports up to four streams of accelerated 3D audio for amazing environmental effects.

However, many other audio adapter vendors are enhancing the effects of EAX by adopting Sensaura's Virtual Ear engine. Virtual Ear enables the user to adjust the apparent position of sound by adjusting the size and shape of the "ear" used to listen to sound. Virtual Ear is currently available on audio adapters from AOpen, Yamaha, Voyetra Turtle Beach, Guillemot/Hercules, and others. Virtual Ear can be purchased as an upgrade for existing audio adapters that use the ADI SoundMax 2, SoundMax 3, and Yamaha YMF 724 and 744 chips.

3D Audio Processing

A second important issue for game players is how the sound cards produce 3D audio. As with 3D video, there are two major methods:

  • Host-based processing (which uses the CPU to process 3D, which can slow down overall system operation)

  • Processing on the audio adapter (referred to as 3D acceleration)

Some 3D audio cards perform some or all of the processing necessary for 3D using the host's CPU, whereas others use a powerful DSP that performs the processing on the audio adapter itself.

Cards that use host-based processing for 3D can cause major drops in frame rate (frames per second of animation displayed onscreen by a 3D game) when 3D sound is enabled if you use under 1GHz processors, whereas cards with their own 3D audio processors onboard have little change in frame rate whether 3D sound is enabled or disabled.

Many of the latest chips from major audio adapter and chipset vendors support 3D acceleration, but the number of 3D audio streams supported varies greatly by chip—and it can sometimes be limited by problems with software drivers. A good rule of thumb for realistic gaming is to have an overall average frame rate of at least 30fps (frames per second).

With CPUs running at 1GHz or above, this is easy to achieve with any recent 3D card. However, gamers using older CPUs, such as those running slower than 1GHz, will find that cards using the host CPU for some of the 3D processing will have frame rates that fall below the desired average of 30fps, making for clumsy gameplay.

To see the effect of enabling 3D sound on the speed of popular games, you can use the built-in frame-rate tracking feature found in many games or check online game-oriented hardware review sources, such as Anandtech. Frame rates are closely related to CPU utilization; the more CPU attention your 3D audio card requires, the slower the frame rate will be. As with 3D video, the main users of 3D sound are game developers, but business uses for ultra-realistic sound will no doubt follow.

DirectX Support Issues

The latest version of DirectX, DirectX 9, is designed to give all sound cards with 3D support a major boost in performance. Previous versions of DirectX supported 3D with DirectSound3D, but the performance of DirectSound3D was limited.

Game programmers needed to test the audio adapter to see whether it supported DirectSound3D acceleration and then would either enable or disable 3D sounds based on the host hardware. Starting with DirectX 5.0, DirectSound3D works with third-party 3D acceleration features. Compared to DirectX 8, DirectX 9 improves 3D audio quality and performance. You can download it from the Microsoft DirectX Web site.

Installing the Sound Card

Before you can install a sound card, you must open your computer. In almost all cases today, you will install a PCI audio adapter that supports Plug and Play configuration. Compared to the previous generation of ISA audio adapters, PCI audio adapters use fewer hardware resources, feature a lower CPU utilization rate, and provide better support for advanced 3D gaming APIs.

If your computer has integrated audio, in most cases you should disable it. You could have audio conflicts with AC'97 codec-based solutions and resource conflicts with solutions that emulate the Creative Labs Sound Blaster. If you have several empty bus slots from which to choose, install the audio adapter in the slot that is as far away as possible from the other cards in the computer.

This reduces any possible electromagnetic interference; that is, it reduces stray radio signals from one card that might affect the sound card. The analog components on audio adapters are highly susceptible to interference, and even though they are shielded, they should be protected as well as is possible.

Next, you must remove the screw that holds the metal cover over the empty expansion slot you've chosen. Remove your audio adapter from its protective packaging. When you open the bag, carefully grab the card by its metal bracket and edges.

Do not touch any of the components on the card because any static electricity you might transmit can damage the card. Also, do not touch the gold-edge connectors. You might want to invest in a grounding wrist strap, which continually drains you of static build-up as you work on your computer.

Before you make your final decision about which slot to use for your audio adapter, take a careful look at the external cables you must attach to the card. Front and rear speakers, microphone, game controller, line in, S/PDIF, and other cables that attach to your system can interfere with (or be interfered by) existing cables already attached to your system.

It's usually best to choose a slot that allows you to route the audio cables away from other cables. If you're installing a Sound Blaster Live! or Audigy series card that uses an internal 5 1/4'' breakout box (Live! Drive or Audigy Drive), be sure the ribbon cable from the drive bay used for the breakout box can comfortably reach the connector on the sound card.

You might have to move a CD-ROM, CD-RW, or DVD drive to a different drive bay to free up a drive bay needed by the breakout box. If your system has an internal CD-ROM drive with an analog audio cable, connect the audio cable to the adapter's CD Audio In connector. This connector is a four-pin connector and is keyed so that you can't insert it improperly.

Note that no true standard exists for this audio cable, so be sure you get the correct one that matches your drive and adapter. If you need to purchase one, you can find cables with multiple connectors designed for various brands of CD-ROM drives. This will allow you to play music CDs through the sound card's speakers and to use analog ripping if you want to create MP3 files from your CDs.

Many recent CD-ROM and DVD drives also have a digital audio connector that supports a two-wire connector. Attach one end of the digital audio cable to the rear of the drive and the other end to the CD SPDIF or CD Digital Audio connector on the sound card. This enables you to perform digital ripping if you want to create MP3 files from your CDs.

Next, insert the adapter's edge connector in the bus slot, but first touch a metal object, such as the inside of the computer's cover, to drain yourself of static electricity. When the card is firmly in place, attach the screw to hold the expansion card and then reassemble your computer.

Connecting to Speakers

After the adapter card is installed, you can connect small speakers to the external speaker jack(s). Typically, sound cards provide 4 watts of power per channel to drive bookshelf speakers. If you are using speakers rated for less than 4 watts, do not turn up the volume on your sound card to the maximum; your speakers might burn out from the overload.

You'll get better results if you plug your sound card into powered speakers—that is, speakers with built-in amplifiers. If your sound card supports a four-speaker system, check the documentation to see which jack is used for the front speakers and which for the rear speakers. To use the rear speakers for 3D audio, adjust the properties with the mixer control software supplied with your sound card.

When the sound card installation is finished, you should have a speaker icon in the Windows System Tray. If the speaker icon (indicating the Volume Control) isn't visible, you can install it through the Control Panel's Add/Remove Programs icon. With Windows 9x/Me, select the Windows Setup tab and open the Multimedia section.

Then, check the box labeled Volume Control. With Windows XP, open the Sounds and Audio Devices icon in Control Panel, click the Volume tab, and click the Place Volume icon in the taskbar box. In some cases you might be asked to insert the Windows CD-ROM if additional drivers are required to complete the installation.

If you use digital sound sources or output such as Dolby 5.1, CD digital, or S/PDIF, open the properties sheet for your mixer device and enable display of these volume controls. Use the Volume Control to ensure your speakers are receiving a sound signal. The mixer sometimes defaults to Mute. You can usually adjust volume separately for wave (WAV) files, MIDI, microphone, and other components.

Using Your Stereo

Another alternative is to patch your sound card into your stereo system for greatly amplified sound and for support of advanced Dolby Digital sound for DVD playback. Check the plugs and jacks at both ends of the connection. Most stereos use pin plugs, also called RCA or phono plugs, for input.

Although pin plugs are standard on some sound cards, most use miniature 1/8'' phono plugs, which require an adapter when connecting to your stereo system. For example, from Radio Shack you can purchase an audio cable that provides a stereo 1/8'' miniplug on one end and phono plugs on the other (Cat. No. 42-2481A).

If you want to attach your sound card to Dolby 5.1 speakers, be sure you use cabling designed for the S/PDIF connectors on your sound card. Some might use RCA-type plugs, whereas others use an optical cable with a square end. Make sure that you get stereo—not mono—plugs, unless your sound card supports only mono.

To ensure that you have enough cable to reach from the back of your PC to your stereo system, get a 6-ft. long cable. Hooking up your stereo to an audio adapter is a matter of sliding the plugs into the proper jacks. If your audio adapter gives you a choice of outputs—speaker/headphone and stereo line-out—choose the stereo line-out jack for the connection.

This will give you the best sound quality because the signals from the stereo line-out jack are not amplified. The amplification is best left to your stereo system. In some cases, you'll attach a special DIN plug to your audio adapter that has multiple connections to your stereo system.

Connect this cable output from your audio adapter to the auxiliary input of your stereo receiver, preamp, or integrated amplifier. If your stereo doesn't have an auxiliary input, other input options include—in order of preference—tuner, CD, or Tape 2. (Do not use phono inputs, however, because the level of the signals will be uneven.)

You can connect the cable's single stereo miniplug to the sound card's stereo line-out jack, for example, and then connect the two RCA phono plugs to the stereo's Tape/VCR 2 Playback jacks. The first time you use your audio adapter with a stereo system, turn down the volume on your receiver to prevent blown speakers.

Barely turn up the volume control and then select the proper input (such as Tape/VCR 2) on your stereo receiver. Finally, start your PC. Never increase the volume to more than three-fourths of the way up. Any higher and the sound might become distorted.