Sweet sixteen. (16-bit sound cards)
by David English
Just when you thought it was safe to buy a sound card, companies start touting their new 16-bit cards. Is an 8-bit card good enough, or should you spend the extra money for a 16-bit card?
When talking about the ability of a sound card to convert sound into digital form, the number of bits describes the amount of audio information a card can handle with each operation, With 8-bit sampling, you're theoretically limited to a signal-to-noise ratio of 48 dB (decibels). That means you'll hear a fair amount of hiss along with the music or speech you record or play back. With 16bit sampling, you can achieve a signal-to-noise ratio of 96 dB, which is theoretically as quiet as a CD audio disc.
There's a similar difference in frequency response, which is a card's ability to capture and reproduce high- and lowfrequency sounds. A 16-bit card can sample 44 kHz, letting you work with frequencies as high as 22 kHz---near the upper limit of human hearing. An 8-bit card is generally limited to sampling at 22 kHz, which yields an upper-end frequency of 11 kHz. Or put another way, an 8-bit card sounds like a cheap FM radio, while a 16-bit card, in theory, sounds as good as a high-end CD player.
I've used qualifying expressions, such as generally and in. theory, to describe these two kinds of sound cards because some manufacturers have been able to stretch the limits of their 8-bit cards, and 16-bit cards can fall short of their potential due to electrical interference from other computer components. Also keep in mind that 16-bit samples take up a lot of disk space. An 8-bit 22-kHz recording in mono takes up a manageable 1.3 megabytes per minute, but a 16-bit 44.1-kHz recording in stereo takes up a whopping 10.5 megabytes per minute. Fortunately, you can choose either sample rate with a 16-bit card, so you can reserve your 16-bit sampling for special occasions. Software and hardware compression can also substantially lower the disk space requirements.
Recently, we've seen the introduction of two 16-bit sound cards for consumers: the Pro AudioSpectrum 16 (Media Vision, 47221 Fremont Boulevard, Fremont, California 94538; 800-845-5870; $349) and the MultiSound (Turtle Beach Systems, 1600 Pennsylvania Avenue, York, Pennsylvania 17404; 717-843-6916; $995). As you can tell by the prices, these cards are aimed at opposite ends of the multimedia market.
The Pro AudioSpectrum 16 is a full-featured multimedia card with connectors for a SCSI CD-ROM drive, a joystick, and a MIDI synthesizer, as well as the usual audio-in and audio-out jacks. It's compatible with programs that support the Windows 3.1, MPC, Sound Blaster, Ad Lib, and ProAudioSpectrum sound standards. Because it doesn't have a DSP (Digital Signal Processor), you'll need a 80386 or 80486 in order to record in stereo at the full 44 kHz.
The MultiSound doesn't have a CD-ROM connector or Sound Blaster, Ad Lib, or Pro AudioSpectrum compatibility, but it does have a DSP (running at a speedy 20 million instructions per second) and a built-in Proteus synthesizer. The DSP will allow the MultiSound to perform on-the-fly compression and decompression once Microsoft chooses an audio compression standard for Windows. As for the Proteus, it's a great-sounding sample-based MIDI synthesizer that, by itself, sells for about the same price as a MultiSound. Listen to the Proteus demo that's included with the Windows driver. You'll be amazed at how a single PC card can accurately emulate 126 different musical instruments and play as many as 32 of them at a time.
Which should you buy? If you need to keep your costs down and require a single board for CD-ROM, Windows, and games, the Pro AudioSpectrum 16 is currently the best deal around. It doesn't cost much more than an 8-bit card, and you'll be ready for applications that support 16~bit sound. If you're willing to spend the extra money, want to be prepared for future compression standards, and can take advantage of the on-board Proteus, buy the MultiSound. It's the premium choice for Windows-based multimedia applications.