Feb 1996 Pullout

Speaker controls should be easily accessible on the front or side of your unit. They should include an on/off switch, a volume control, a headphone jack, and bass and treble controls. Other options include a mute button, mini-stereo input jacks, an external microphone jack and sound mixing controls.

Speakers, like cars, are priced in three broad categories. A basic model runs from $40 to $80 and provides better sound than your PC's speaker, but that's the best you can say for it. The midrange option costs up to about $200 and will provide good fidelity and sound. Top-of-the-line speakers will set you back about $300 to $600; for that you'll get sound quality that will set your wheels spinning.

Power output is generally rated in watts per channel, with a higher number of watts indicating more power. The range is 1 to 20 watts per channel. Generally, 3 to 5 watts should suffice for casual multimedia users, while speakers for large presentations should have at least 10 watts. Each company has its own formula for rating power, so don't use these numbers as your only measurement.

Look for speakers that offer built-in amplification. This feature reduces distortion and lets you punch up the sound volume more than you could with only the minimum voltage emitted by your sound card.

When it comes to speakers, it's all in the ears of the beholder. The best way to find the right speakers is to listen. Bring a familiar music CD with you to use in comparing products. If you plan to use your CD-ROM player mainly for music, choose speakers with a wide frequency range (which is measured in hertz). Game players will want a powerful bass range, which means investing in a system that comes with a separate subwoofer. Finally, if you mostly use multimedia CD-ROMs, look for the clearest sound you can find.

Also, make sure that the speakers you choose are magnetically shielded, which will protect your monitor, hard drive and magnetic media (such as diskettes) from damage and eliminate vibration. Another consideration is frequency response, or the lowest and highest sound frequencies the speaker can reproduce. High-end speakers provide 70Hz to 20kHz; the human ear can distinguish from 40Hz to 20kHz.

Although 3-D sound is old hat to stereophiles, it's just recently become widely available to multimedia PC users. First-person games, like Doom and Descent, employ this technology to create immersive experiences for their users. By localizing sounds, 3-D audio makes you feel like you're moving in conjunction with related objects on the screen. Despite its name, 3-D audio moves sounds to the PC's left and right, but not over and under the system. The effect remains realistic because human hearing is more attuned to side-to-side listening.

Several approaches strive for the 3-D sound effect, including those from QSound, Spatializer, Dolby and SRS. In addition, Microsoft is currently working on a 3-D audio API for Windows 95 (due out sometime this year) that will encourage software developers to create products incorporating 3-D audio.

Three-dimensional sound is implemented in several places within your PC, including through a software application, on the motherboard, on the sound card and in the speakers. If your sound signals are processed by a number of different 3-D systems in the computer, the resulting audio may seem overprocessed or distorted. Make sure the 3-D sound systems in your PC don't collide like this.