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Upgrading & Repairing PCs Eighth Edition

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Audio Hardware

One of the problems with the PC standard is that when it was first created, it did not include audio capabilities other than rudimentary beeping or tone generation. Part of this was due to the fact that the PC standard originated in 1981, and other computers of that time had similar rudimentary capabilities. Systems that were designed later, such as the Macintosh which debuted in 1984, did include high-quality audio capabilities as an integral part of the system hardware and software. Although there still is no universal audio hardware and software standard for PC-compatible systems, the inherent expandability of the PC platform allows audio capability to be easily added, and at least one de facto standard has emerged. This chapter focuses on these products and how they are installed and operated.

Sound Card Applications

At first, consumer sound cards were used only for games. Several companies including AdLib, Roland, and Creative Labs had introduced products by the late 1980s. In 1989, Creative Labs introduced the Game Blaster, which provided stereo sound to a handful of computer games. The question for many buyers was, "Why spend $100 for a card that adds sound to a $50 game?" More importantly, because no sound standards existed at the time, a sound card might be useless with other games.

NOTE: About the same time, the Musical Instrument Digital Interface (MIDI) interfaces became available for the PC, but were used in very specialized recording applications.

A few months after releasing the Game Blaster, Creative Labs announced the Sound Blaster sound card. The Sound Blaster was compatible with the AdLib sound card and Creative Labs' own Game Blaster card. It included a built-in microphone jack and a MIDI (Musical Instrument Digital Interface) for connecting the PC to a musical synthesizer. Finally, the sound card had uses other than games.

Unfortunately, there is no single standard for PC-compatible sound cards. As in other aspects of the computer industry, standards are often developed by the market leader in a particular segment of the marketplace. These are called de facto standards. For example, Hewlett-Packard printers use a command language and graphics language that has become a de facto standard simply because many of their printers have been sold and most software supports them. Other printer manufacturers then strive to make their printers emulate the Hewlett-Packard printers so they don't require unique commands and they can use the same commands and drivers as a Hewlett-Packard printer. This is how a de facto standard is born. It is essentially based on popularity. While other printer command standards exist, the Hewlett-Packard standard is supported by most PC-compatible printers.

Over the last few years, several sound card manufacturers have fought for dominance, and there are several popular brands. Although several different companies make audio boards, the ones from Creative Labs have dominated the marketplace and have become the de facto standard. Thus, most audio boards from other companies emulate the Creative Labs Sound Blaster boards. Like the Hewlett-Packard printer standard, the Creative Labs Sound Blaster interface is the one that most hardware products emulate, and the one that most drivers are written for.

A sound card has many uses, including the following:

Games

The sound card was originally designed to play games. In fact, many sound cards include a game adapter interface, which is a connector for adding a game control device (usually a joystick or control paddles). This is a potential area of conflict because other cards such as the multi-I/O type cards used in many PCs that have serial ports, parallel ports, and so on also have a game interface. This will result in an I/O Port address conflict since all game interfaces use the same I/O Port addresses. In these cases, it is usually best to use the game adapter interface on the sound card and disable any other in your system.

By adding a sound card, the game playing takes on a new dimension. The sounds add a level of realism that would otherwise be impossible, even with the best graphics. For example, some games use digitized human voices and dialog. In addition to realistic sounds and effects, games can have musical scores, which add to the excitement and entertainment.

Multimedia

A sound card is a prerequisite if you want to turn your PC into a Multimedia PC (MPC). What is multimedia? The term embraces a number of PC technologies, but primarily deals with video, sound, and storage. Basically, multimedia means the ability to merge images, data, and sound on a computer. In a practical sense, multimedia simply means adding a sound card and a CD-ROM drive to your system.

An organization called the Multimedia PC Marketing Council was originally formed by Microsoft to generate standards for MPCs. The council created several MPC standards and license its logo and trademark to manufacturers whose hardware and software conform to these standards. This allows compatible hardware and software to be developed for multimedia operation on PC-compatible systems.

More recently, the MPC Marketing Council has formally transferred responsibility for its standards to the Software Publishers Association's Multimedia PC Working Group. This group includes many of the same members as the original MPC, and will now be the body governing the MPC specifications. The first thing this group has done is create a new MPC standard.

The MPC Marketing Council originally developed two primary standards for multi- media. They are called the MPC Level 1 and MPC Level 2 standards. Now under the direction of the Software Publishers Association (SPA), these first two standards have been augmented by a third standard called MPC Level 3, which was introduced in June 1995. These standards define the minimum capabilities for an MPC. Table 12.1 shows these standards.

Table 12.1  Multimedia Standards

MPC Level 1 MPC Level 2 MPC Level 3
Processor 16MHz 386SX 25MHz 486SX 75MHz Pentium
RAM 2M 4M 8M
Hard Disk 30M 160M 540M
Floppy Disk 1.44M
3 1/2-inch		 1.44M
3 1/2-inch		 1.44M
3 1/2-inch
CD-ROM Drive Single-Speed Double-Speed Quad-Speed
Audio 8-bit 16-bit 16-bit
VGA Video 640x480; 640x480; 640x0;
Resolution 16 colors 64K colors 64K colors
Other I/O Serial, Parallel, MIDI, Game Serial, Parallel, MIDI, Game Serial, Parallel, MIDI, Game
Software Microsoft
Windows 3.1		 Microsoft
Windows 3.1		 Microsoft
Windows 3.1
Date Introduced 1990 May 1993 June 1995

The MPC-3 specifications should be considered the bare minimums for any multimedia system today. In fact, I would normally recommend a system that exceeds the Level 3 standards in several areas, such as CPU, RAM, hard disk size, and video capability. Note that although speakers are technically not a part of the MPC specification, they are certainly required for sound reproduction!

MIDI

If you're musically inclined, you'll enjoy MIDI (Musical Instrument Digital Interface). Developed in the early 1980s, MIDI essentially is a powerful programming language that lets your computer store and edit or play back music in tandem with a MIDI-compatible electronic musical instrument, typically a keyboard synthesizer.

The MPC specs mentioned earlier call for MIDI support. With MIDI, you can compose and edit music for presentations, learn about music theory, or turn your PC into a one-stop music mixing studio.

MIDI makes a musical note sound as though it comes from any of a wide array of instruments. The MPC specifications require a sound card to contain an FM MIDI synthesizer chip and be able to play at least six notes simultaneously.

To connect a MIDI device to a PC, you need a sound card that has two round serial ports in back--a MIDI input port and a MIDI output port. In addition to a keyboard, you'll need sequencing software to modify the tempo, sound, and volume of your recordings, or to cut and paste together various prerecorded music sequences.

Unlike other sound files, MIDI messages require little disk space. An hour of stereo music stored in MIDI requires less than 500K. (To contrast, a Microsoft Windows digital sound WAV file consumes more than 1,000 times that space.) Many games use MIDI sounds to conserve on disk space.

The quality of sound reproduction from MIDI files can vary greatly from card to card. This depends largely on whether your card uses wavetable synthesis or FM synthesis for MIDI reproduction.

Most sound boards generate sounds by using FM synthesis, a technology first pioneered in 1976. By using one sine wave operator to modify another, FM synthesis creates an artificial sound that mimics an instrument. Over the years, the technology has progressed (some FM synthesizers now use four operators) to a point where FM synthesis sounds good, but it still sounds artificial.

More realistic, inexpensive sound was pioneered by Ensoniq Corp., the makers of professional keyboards, in 1984. Using a technology that had been theorized at about the same time as FM synthesis, Ensoniq found a way to sample any instrument--including pianos, violins, guitars, flutes, trumpets, and drums--and to store the digitized sound in a wave- table. Stored either in ROM chips or on disk, the wavetable supplies an actual digitized sound of an instrument when called by the application. Soon after Ensoniq's discovery, other keyboard makers replaced their FM synthesizers with wavetable synthesis.

Wavetable synthesis won't make every sound on your PC more realistic--only the MIDI sounds, which are often used in games. Windows WAV files are actual stored sounds and don't benefit from wavetable synthesis.

Presentations

Businesses are discovering that combining graphics, animation, and sound is more impressive, and often less expensive, than a slide show. A sound card adds impact to any presentation or classroom.

A variety of business-presentation software and high-end training and authoring packages already exist. And you don't have to be a programmer to get your own show on the road. Even such popular software packages as CorelDRAW! and PowerPoint now include sound and animation features for their presentation files.

Some presentation software, such as PowerPoint and Corel Presents!, packages support WAV, AVI, and MIDI files. With these products, you can synchronize sounds with objects. When a picture of a new product is displayed, for example, you can play a roaring round of applause. You can even pull in audio from a CD in your CD-ROM drive. Such presentation software programs often include clip-media libraries.

A sound card can make tasks (such as learning how to use software) easier. PC software manufacturers have taken an early lead in this area. Many publishers are shipping special CD-ROM versions of some of their products. These versions often include animated online help, replete with music.

You can even take your show on the road. Many laptop and notebook computers today include sound capability and even have built-in CD-ROM drives and speakers. There are also external sound cards and even CD-ROM drives that attach to a laptop computer's parallel port to provide multimedia on the go. Finally, there are also several PC Card (PCMCIA)-based sound cards and CD-ROM drives on the market.

Recording

Virtually all sound cards have an audio input jack. With a microphone, you can record your voice. Using the Microsoft Windows Sound Recorder, you can play, edit, or record a sound file. These files are saved as WAV files, a type of file format. In the Windows Control Panel, you can assign certain Windows events a specific WAV file (see Figure 12.1). I always get a laugh when I exit Windows and hear the sound of a flushing toilet!

By recording your own sounds, you can create your own WAV files. Then you can use them for certain events. These are some of the standard events:

Start Windows Menu Command Menu Pop-up
Exit Windows Default Sound Exclamation
Open Program Asterisk Maximize
Close Program Critical Stop Question
Minimize Program Error


FIG. 12.1  The Sounds section of the Windows 95 Control Panel adds sound to different Windows events.

Through the same audio input jack, you can attach your stereo system and record a song to a WAV file. You can also purchase prepackaged WAV files. Prerecorded WAV files can also be found on your local electronic bulletin board or online services such as CompuServe and America Online.

You can find audio files, particularly WAV files, at several locations such as:

Voice Annotation

By using WAV files, you can record messages into your Windows documents and spreadsheets. For example, a business executive could pick up a microphone and, by embedding a message in a contract, give his or her secretary explicit instructions. This message is called a voice annotation. I like to think of it as a verbal Post-It note.

With voice annotation, you can embed voice messages, suggestions, or questions in a document and send it to a colleague. To leave such messages, your Windows application must support Windows' Object Linking and Embedding (OLE).

Imagine that you're editing a worksheet in Excel and want to insert a voice note next to a total that looks questionable. Place the cursor in the cell next to the total, then select Edit, Insert, Object, Sound to call up Windows' Sound Recorder. Click the Record button and begin speaking.

Voice Recognition

Some sound cards are capable of voice recognition. You can also get voice recognition for your current sound card in the form of add-on software. Voice-recognition technology is unfortunately still in its infancy, and you will need a fast computer, such as a Pentium, for quick response times.

Voice Recognition is still sensitive to changes in a person's voice, with both illness and stress changing a person's voice enough to throw off most of the "consumer" voice recognition products. Advances in this technology may develop to a point where we'll be able to use continuous speech to control our computer, rather than typing.

Proofreading

Sound cards can be used also as inexpensive proofreaders. Text-to-speech utilities can read back to you a list of numbers or text. This software is included with some sound cards and can be used to read back highlighted words or even an entire file.

This will allow you to more easily spot forgotten words or awkward phrases when you hear a note read back to you. Accountants can double-check numbers, and busy executives can listen to their e-mail while they are doing paperwork.

Audio CDs

One entertaining use of a CD-ROM drive is to play audio CDs while you are working on something else. The music can be piped not only through a pair of speakers but also through a headphone set plugged into the front of your CD-ROM drive. Most sound cards include a CD-player utility, although free versions are available on online services such as CompuServe. These programs usually present a visual display similar to an audio CD player. You operate the controls with a mouse or the keyboard, and can listen to audio CDs while you work on other things.

Sound Mixer

Any time you have multiple sources of sound that you want to play through a single set of speakers, a mixer is necessary. Most mixers are the kind that you see in music videos, or in use by your local DJ.

Most sound cards have a built-in mixer to allow all of the different audio sources, MIDI, WAV, Line IN, and the CD to be played out of the single Line Out. Normally, software is included with the sound card that displays visual sliders like you would see on a standard mixer. This allows you to control the relative volume of each of the sound sources.

Sound Card Concepts and Terms

To understand sound cards, you need to understand various concepts and terms. Terms like 16-bit, CD quality, and MIDI port are just a few. Concepts such as sampling and digital-to-audio conversion (DAC) are often sprinkled throughout stories about new sound products. The following sections describe some common sound card terms and concepts.

The Nature of Sound

To understand a sound card, you need to understand sound itself. Every sound is produced by vibrations that compress air or other substances. These sound waves travel in all directions, expanding in balloon-like fashion from the source of the sound. When these waves reach your ear, they cause vibrations that you perceive as sound.

The two basic properties of any sound are its pitch and its intensity.

Pitch is simply the rate at which vibrations are produced. It is measured in the number of hertz (Hz), or cycles per second. One cycle is a complete vibration back and forth. The number of Hz is the frequency of the tone; the higher the frequency, the higher the pitch. You cannot hear all possible frequencies. Very few people can hear any fewer than 16Hz or any more than about 20KHz (kilohertz; 1KHz equals 1,000Hz). In fact, the lowest note on a piano has a frequency of 27Hz, the highest note, a little more than 4KHz. And frequency-modulation (FM) radio stations broadcast notes up to 15KHz.

The intensity of a sound is called its amplitude. This intensity depends upon the strength of the vibrations producing the sound. A piano string, for example, vibrates gently when the key is struck softly. The string swings back and forth in a narrow arc, and the tone it sends out is soft. If the key is struck forcefully, however, the string swings back and forth in a wider arc. The loudness of sounds is measured in decibels (db). The rustle of leaves is rated at 20db, average street noise at 70db, and nearby thunder at 120db.

Game Standards

Most sound cards support both of the current entertainment audio standards: AdLib and Sound Blaster. The Sound Blaster is a family of sound cards sold by Creative Labs; AdLib sells their own cards as well. To play most games, you must tell your game which of these sound card standards your sound card supports. Sticking with a popular sound card product (like the Sound Blaster line from Creative Labs) will ensure that you always have software support. Most software supports the Sound Blaster or AdLib cards, and because of this, now most other brands' sound cards will emulate one of these popular ones. If you have some off-the-wall brand sound card and it does not emulate either the Sound Blaster or AdLib cards, then you may find many software products that do not specifically support your card.

NOTE: More and more games are being developed for Windows 95. Games that are written for Windows 95 do not require specific compatibility with any sound card. They will work even if your sound card is not Sound Blaster- or AdLib-compatible.

Frequency Response

The quality of a sound card is often measured by two criteria: frequency response (or range) and total harmonic distortion.

The frequency response of a sound card is the range in which an audio system can record or play at a constant and audible amplitude level. Many cards support 30Hz to 20KHz. The wider the spread, the better the sound card.

The total harmonic distortion measures a sound card's linearity, the straightness of a frequency response curve. In layman's terms, the harmonic distortion is a measure of accurate sound reproduction. Any nonlinear elements cause distortion in the form of harmonics. The smaller the percentage of distortion, the better.

Sampling

With a sound card, a PC can record Waveform audio. Waveform audio (also known as sampled or digitized sound) uses the PC as a tape recorder. Small computer chips built into a sound card, called analog-to-digital converters (ADCs), convert analog sound waves into digital bits the computer can understand. Likewise, digital-to-analog converters (DACs) convert the recorded sounds to something audible.

Sampling is the process of turning the original analog sound waves (see Figure 12.2) into digital (on/off) signals that can be saved and later replayed. Snapshots of the analog sounds are taken and saved. For example, at time X the sound may be measured with an amplitude of Y. The higher (or more frequent) the sample rate, the more accurate the digital sound is to its real-life source.

FIG. 12.2  Sampling turns a changing sound wave into measurable digital values.

8-Bit versus 16-Bit

The original MPC specifications required 8-bit sound. This doesn't mean the sound card must fit into an 8-bit instead of a 16-bit expansion slot. Rather, 8-bit audio means that the sound card uses 8 bits to digitize each sound sample. This translates into 256 possible digital values to which the sample can be pegged (less quality than the 65,536 values possible with a 16-bit sound card). Generally , 8-bit audio is adequate for recorded speech, whereas 16-bit sound is best for the demands of music. Figure 12.3 shows the difference between 8- and 16-bit sound.

FIG. 12.3  16-bit resolution allows more accurate sound reproduction than 8-bit resolution.

Many of the older sound cards did 8-bit sound reproduction only. Today, I would not recommend anything less than a 16-bit card, which offers very high resolution.

Besides resolution, the sampling rate or frequency determines how often the sound card measures the level of the sound being recorded or played back. Basically, you have to sample at about two times the highest frequency you want to produce, plus an extra 10 percent to keep out unwanted signals. Humans can hear up to 20,000 cycles per second, or 20KHz. If you double this number and add 10 percent, you get a 44.1KHz sampling rate, the same sampling rate used by high-fidelity audio CDs.

Sound recorded at 11KHz (capturing 11,000 samples per second) is fuzzier than sound sampled at 22KHz. A sound sampled in 16-bit stereo (two channel) at 44KHz (CD-audio quality) requires as much as 10.5M per minute of disk space! The same sound sample in 8-bit mono (single channel) at 11KHz takes 1/16th the space. If you were to add a one-minute hi-fi voice annotation to your spreadsheet, you'd find a spreadsheet whose size had increased by more than 10M.

The CD-ROM Connection

In addition to a sound card, the other foundation of multimedia is a CD-ROM (compact disk read-only memory) drive.

CD-ROM drives provide access to a wealth of text, graphics, sound, video, and animation. Like a sound card, a CD-ROM drive is essential for any multimedia PC.

Many sound cards double as a CD-ROM controller, or interface, card. Some sound cards, however, use a proprietary connection that accommodates only certain proprietary interface CD-ROM drives. For a wider selection of drives, consider a sound card that includes an IDE (Integrated Drive Electronics) or SCSI-2 (Small Computer Systems Interface-2) connector. If you are also going to attach other SCSI devices such as hard disks, tape drives, or scanners, then I recommend staying with a separate stand-alone SCSI-2 adapter. The software driver support and performance will be much better than on the Sound/SCSI combo cards.

For more information on CD-ROM drives, see Chapter 17 "CD-ROM Drives."

Sound File Formats

There are several file formats for storing and editing digitized sound. The most notable is the WAV format supported by Windows. (WAV is short for waveform audio.) One audio minute saved to a WAV file requires 2.5M to 10M or more of disk space, depending on the recording options you select. Windows 95 offers recordings at several different rates and bit depths.

Sound Reproduction

As mentioned previously, there are two methods for sound reproduction. The older, cheaper, and less desirable method called Frequency Modulation is losing favor as people move to wavetable sound. When looking for a card today, look for wavetable-based sound.

Compression/Decompression

Because one minute of stereo audio can consume up to 11M of disk space, several sound card makers use Adaptive Differential Pulse Code Modulation (ADPCM) compression to reduce file size by more than 50 percent. However, a simple fact of audio life is that when you use such compression, you lose sound quality.

Because the sound quality can be degraded, there is no ADPCM standard. Creative Labs uses a proprietary hardware approach, while Microsoft is pushing the Business Audio ADPCM design developed with Compaq.

The most popular compression standard is the Motion Pictures Experts Group (MPEG) standard, which works with both audio and video compression and is gaining support in the non-PC world from products like the Philips CD-I player. MPEG sports a potential compression ratio of 12:1, and due to this, several full-motion-video MPEG CD-ROM titles are now available.

Sound Card Characteristics

What are some key features to consider in a sound card? Although some aspects are subjective, the following sections describe some key buying points.

Compatibility

Although there are no official sound card standards, the popular Sound Blaster card has become a de facto standard. The Sound Blaster--the first widely distributed sound card--is supported by the greatest number of software programs. A sound card advertised as Sound Blaster-compatible should run virtually any application that supports sound. Many sound cards also support the MPC Level 2 or Level 3 specifications, allowing you to play sound files in Windows and more. Some sound cards, by excluding a MIDI interface, barely fall short of the MPC specs. Other compatibility standards to look for are AdLib and Pro AudioSpectrum.

CAUTION: Beware of sound cards that require special drivers to be Sound Blaster-compatible. These drivers can cause problems and will take up additional memory that otherwise would be available.

Sampling

The most important sound card quality is its sampling capability. The rate at which the card samples (measured in KHz) and the size of its sample (expressed in bits) determine the quality of the sound. The standard sampling rates for sound cards are 11.025KHz, 22.050KHz, and 44.1KHz; sample sizes are 8, 12, and 16 bits.

Inexpensive monophonic cards generally sample at 8 bits up to speeds of 22.050KHz, which is fine for recording voice messages. Some stereo-capable cards sample at 8 bits and run at speeds of 22.050KHz in stereo and up to 44.1KHz in mono. Other cards can sample 8 bits at 44.1KHz speeds in both stereo and mono. The latest generation of cards do it all; they can record CD-quality audio of 16 bits at 44.1KHz.

If you do buy a card that supports 16-bit sampling and plan on doing any recording, make sure you have plenty of hard disk space. The higher the resolution of sampling, the more hard disk space needed to store the file. The sampling rate also affects file size; sampling at the next higher rate doubles the file size.

Stereo versus Mono

You'll also have to consider buying a monophonic or stereophonic sound card. Inexpensive sound cards are monophonic, producing sound from a single source. Still, monophonic cards produce better sound than your PC's speaker.

Stereophonic cards produce many voices, or sounds, concurrently and from two different sources. The more voices a card has, the higher the sound fidelity. Each stereo chip in a sound card is capable of 11 or more voices. To get 20 or more voices, manufacturers had to resort to two FM synthesizer chips. Today, a single chip produces 20 voices, providing truer stereo sound.

The number of voices a stereo card has is especially important for music files because the voices correspond to the individual instruments the card can play.

Most cheaper sound cards use FM synthesis to imitate the musical instruments played. Most use synthesizer chips developed by Yamaha. The least expensive sound cards use the monophonic 11-voice YM3812 or OPL2 chip. Better sound cards use the stereophonic 20-voice YMF262 or OPL3 chip.

Imitated musical instruments are not as impressive as the real thing. Wavetable sound cards often use digital recordings of real instruments and sound effects. Often, several megabytes of these sound clips are embedded in ROM chips on the card. For example, some sound cards use the Ensoniq chip set (a type of circuit design) that does wavetable synthesis of musical instruments. Instead of pretending to play a trombone D flat, the Ensoniq chip set has a little digitized recording of an actual instrument playing that note.

If your primary interest in a sound card is for entertainment or for use in educational or business settings, FM synthesis quality may be good enough.

Stereo sound cards vary in sampling rates and sizes. Some stereo cards do not work in mono mode. Also, moving from mono to stereo sound means an increase in the size of the sound files. As with 16-bit resolution, stereo sound is not supported by most software applications. However, a stereo card playing mono software does generate better sound than a mono card.

Another consideration when buying the more expensive stereo cards is that they generally come with additional interfaces, such as connections to a SCSI device (such as a CD-ROM drive) or a MIDI device (such as a keyboard). In most cases, you will get better performance from a CD-ROM drive by connecting it to a motherboard IDE port or a separate high-performance SCSI host adapter.

CD-ROM Connector

Most stereo sound cards not only provide great sound but also can operate your CD-ROM drive. Although many cards come with a SCSI port for any SCSI device, such as a CD-ROM drive, others support only a proprietary CD-ROM interface, such as Mitsumi or Sony CD-ROM interfaces. If you own a CD-ROM drive, make sure it's compatible with the sound card you plan to buy. If you plan to add a CD-ROM drive or expect to upgrade your drive, keep in mind that a proprietary interface will limit your choices, perhaps to a single CD-ROM brand.

If you're seeking to add both a sound card and a CD-ROM drive, consider multimedia upgrade kits. These kits bundle a sound card, CD-ROM drive, CD-ROM titles, software, and cables in an attractively priced package. By buying a multimedia upgrade kit rather than disparate components, you may save some money. And you'll know that the components will work together, especially if the kit includes proper documentation.

Data Compression

Most sound cards today can easily produce CD-quality audio, which is sampled at 44.1KHz. At this rate, recorded files (even of your own voice) can consume as many as 11M for every minute of recording. To counter this demand for disk space, many sound cards include a data-compression capability. For example, the Sound Blaster ASP 16 includes on-the-fly compression of sound in ratios of 2:1, 3:1, or 4:1.

MIDI Interface

The Musical Instrument Digital Interface (MIDI) is a standard for connecting musical instruments to PCs. Many stereo cards come with MIDI, synthesizer, and sequencing software for composing music. Some cards include only a MIDI interface; you have to purchase the hardware separately to hook up other MIDI devices. Other sound cards may exclude the MIDI.

MIDI allows your computer to store, edit, and play back music through a MIDI instrument such as a keyboard synthesizer. MIDI is more like a networking programming language, allowing you to add more instruments, including drum machines and special sound effects generators.

Bundled Software

Sound cards usually include several sound utilities so that you can begin using your sound card right away. Most of this software is DOS-based, but Windows-based versions are available with some cards. The possibilities include:

Multi-Purpose Digital Signal Processors

One recent addition to many sound boards is the digital signal processor (DSP). DSPs add intelligence to your sound card, freeing your computer from work-intensive tasks, such as filtering noise from recordings or compressing audio on-the-fly.

About half of most general-purpose sound cards use DSPs. The Cardinal Technologies Sound Pro 16 and Sound Pro 16 Plus, for example, use the Analog Devices ADSP2115 digital signal processor. The Sound Blaster AWE32's programmable DSP features compression algorithms for processing text-to-speech data and enables the card's QSound surround-sound 3-D audio, along with reverb and chorus effects. DSPs allow a sound card to be a multi-purpose device. IBM uses its DSP to add a 14.4Kbit/sec modem, 9.6Kbps fax, and a digital answering machine to its WindSurfer Communications Adapter.

Are DSPs worth the extra price? On low-powered PCs (those less powerful than a 486SX/25) or in true multitasking environments like Windows 95, Windows NT, or OS/2 Warp, a DSP can make real-time compression possible--a feature valuable for voice annotation. Note that many cards can be purchased without the DSP chip and can have it added later as an upgrade.

Sound Drivers

Most sound cards include universal drivers for DOS and Windows applications. Find out what drivers are included with your card. Windows 95 already includes drivers for the most popular sound cards, such as Sound Blaster. Other drivers are available on a separate driver disk available from Microsoft or from Microsoft's Product Support download service.

Connectors

Most sound cards have the same connectors. These 1/8-inch minijack connectors provide ways to pass sound from the sound card to speakers, headphones, and stereo systems and to receive sound from a microphone, CD player, tape player, or stereo. The four types of connectors your sound card typically could or should have are shown in Figure 12.4:

FIG. 12.4  The basic features most sound cards have in common.

Sometimes the joystick port can accommodate two joysticks if you order the optional Y-adapter. To use this connector as MIDI, you'll need to buy the optional MIDI cable. Some sound cards do not provide MIDI. If you're not interested in making music (and spending a few hundred dollars more for the MIDI keyboard), you may want to consider these models. And don't worry about the lack of a joystick port. These are already found in some PCs as a part of a Multi-I/O card; otherwise, you can buy a separate stand-alone game card.

Volume Control

A thumbwheel volume control is provided on some sound cards, although sophisticated sound cards have no room for such a control. Instead, a combination of keys or a visual slider control can be used to adjust the sound. By pressing these key combinations, you adjust the volume from within a game, Windows program, or any other application.

Sound Card Options

You'll seldom buy just a sound card. You'll need--or want--other accessories that raise the cost of your PC sound system. At the very least, you'll have to invest in a set of speakers or headphones. At most, you may want to purchase a MIDI synthesizer keyboard.

Speakers

Successful business presentations, multimedia applications, and MIDI work demand external high-fidelity stereo speakers. Although you can use standard stereo speakers, they are too big to fit on or near your desk. Smaller bookshelf speakers are better.

Sound cards offer little or no power to drive external speakers. Although some sound cards have small 4-watt amplifiers, they are not powerful enough to drive quality speakers. Also, conventional speakers sitting near your display may create magnetic interference, which can distort colors and objects on-screen or jumble the data recorded on your nearby floppy disks.

To solve these problems, computer speakers need to be small, efficient, and self-powered. Also, you need to provide magnetic shielding, either in the form of added layers of insulation in the speaker cabinet or by electronically canceling out the magnetic distortion.

CAUTION: Although most computer speakers are magnetically shielded, do not leave recorded tapes, watches, personal credit cards, or floppy disks in front of the speakers for long periods of time.

Quality sound depends on quality speakers. A 16-bit sound card may provide better sound to computer speakers, but even an 8-bit sound card sounds good from a good speaker. Conversely, an inexpensive speaker makes both 8-bit and 16-bit sound cards sound tinny.

The dozens of models on the market range from less expensive minispeakers from Sony and Koss to larger self-powered models from companies such as Bose. To evaluate speakers, you need to know the lingo. Speakers are measured by three criteria:

Two or four C batteries are often used to power computer speakers. Because these speakers require so much power, you may want to invest in an AC adapter, although more-expensive speakers include one. With an AC adapter, you won't have to buy new batteries every few weeks. If your speakers didn't come with an AC adapter, you can pick one up from your local Radio Shack or hardware store. Be sure that the adapter you purchase matches your speakers in voltage and polarity.

You can control your speakers in various ways, depending on their complexity and cost. Typically, each speaker has a volume knob, although some share one volume control. If one speaker is farther away than the other, you may want to adjust the volume accordingly. Many computer speakers include a dynamic bass boost (DBB) switch. This button provides a more powerful bass and clearer treble, regardless of the volume setting. Other speakers have separate bass and treble boost switches or a three-band equalizer to control low, middle, and high frequencies. When you rely on your sound card's power rather than your speaker's built-in amplifier, the volume and dynamic bass boost controls have no effect. Your speakers are at the mercy of the sound card's power.

A 1/8-inch stereo minijack connects from the sound card output jack to one of the speakers. The signal is then split and fed through a separate cable from the first speaker to the second one.

Before purchasing a set of speakers, check that the cables between the speakers are long enough for your computer setup. For example, a tower case sitting alongside one's desk may require longer speaker wires than a desktop computer.

Beware of speakers that have a tardy built-in "sleep" feature. Such speakers, which save electricity by turning themselves off when they are not in use, may have the annoying habit of clipping the first part of a sound after a period of inactivity.

Headphones are an option when you can't afford a premium set of speakers. Headphones also provide privacy and allow you to play your sound card as loud as you like.

Microphone

Some sound cards do not include a microphone. You'll need one to record your voice to a WAV file. Selecting a microphone is quite simple. You need one that has a 1/8-inch minijack to plug into your sound card's microphone, or audio in, jack. Most have an on/off switch.

Like speakers, microphones are measured by their frequency range. This is not an important buying factor, however, because the human voice has a limited range. If you are recording only voices, consider an inexpensive microphone that covers a limited range of frequencies. An expensive microphone's recording capabilities extend to frequencies outside the voice's range. Why pay for something you won't be needing?

If you are recording music, invest in an expensive microphone, although an 8-bit sound card can record music just as well with an inexpensive microphone.

Your biggest decision is to select a microphone that suits your recording style. If you work in a noisy office, you may want a unidirectional microphone that will prevent extraneous noises from being recorded. An omnidirectional mike is best for recording a group conversation.

Most higher-priced sound cards include a microphone of some type. This can be a small lapel microphone, a hand-held microphone, or one with a desktop stand. If you want to leave your hands free, you may want to shun the traditional hand-held microphone for a lapel model. If your sound card does not come with a microphone, see your local stereo or electronics parts store. Be sure that any microphone you purchase has the correct impedance to match the sound card input.

Joysticks

Many sound cards include a joystick, or game, port. (This joystick port often doubles as a connection to a MIDI device.) A joystick is ideally meant for game playing, such as simulating flying a Cessna aircraft. Joysticks, like speakers, are best chosen through hands-on experience.

A joystick has a fire button on top of a center wand you move in any of eight directions, with a second button or pair of buttons located on the base.

Good joysticks have resistance that increases the further you move the center wand from dead center. Some joysticks include suction cups that mount the unit on your desk. If you're short on desk space, you may prefer a smaller joystick that fits in your hand. If you are left-handed, look for an ambidextrous joystick, not one that is contoured for right-handers.

Some joysticks are meant especially for flight-simulation or driving games. These simulate an aircraft control yoke, or an automobile steering wheel. They often include pedals for other functions as well.

MIDI Connector

If you are interested in MIDI to create synthesized music, you'll need to connect your musical keyboard or other MIDI device to your sound card. The joystick port on sound cards has unused pins that can be used to send and receive MIDI data. By connecting a MIDI cable to the joystick port, you can connect your PC to a MIDI device. The cable has three connectors: a joystick connector, and MIDI In and Out connectors.

Synthesizer

If you are considering MIDI, you will want to get a MIDI keyboard synthesizer if you intend on composing or playing music, although you can play back MIDI scores without one. To make MIDI scores, you also need sequencer software to record, edit, and play back MIDI files. (Some sound cards include sequencing software.) A MIDI file contains up to 16 channels of music data, so you can record many different instruments and play them back. By using the keyboard, you can enter the notes for various instruments.

To enhance MIDI sounds for the Sound Blaster cards, Creative Labs offers the Wave Blaster. The Wave Blaster plugs into the Sound Blaster card. When MIDI music is played, it looks to the Wave Blaster for any of 213 CD-quality digitally recorded musical instrument sounds. Without the Wave Blaster, the Sound Blaster would imitate these sounds through FM synthesis. With the Wave Blaster, music sounds as though it's being played by real instruments--because it is. Many sound cards are available with built-in full MIDI and wavetable support.

Several MIDI keyboards are available from companies such as Roland, Yamaha, Casio, or others. These keyboards range in price from $100 or less to many thousands of dollars.

Some sound cards have optional memory that can be added to store more sound samples.

Sound Card Installation

Installing a sound card is no more intimidating than installing an internal modem or a VGA card. Typically, you follow these steps to install a sound card:

1. Open your computer.

2. Configure your sound card.

3. Install the sound card and attach the CD-ROM drive, if present.

4. Close your computer.

5. Install the sound card software.

6. Attach your speakers and other sound accessories.

Installing the Sound Card

Once your computer is open, you can install the sound card. Your sound card may be either an 8-bit or 16-bit expansion card. Select a slot that matches the type of card you have. You don't want to put a 16-bit card (one with dual edge connectors) into an 8-bit slot (one with a single edge connector). An 8-bit card, however, can fit into either an 8-bit or 16-bit slot.

If you have several empty slots from which to choose, you may want to place the new card in one as far away as possible from the others. This reduces any possible electromagnetic interference; that is, it reduces stray radio signals from one card that might affect the sound card.

Next, you must remove the screw that holds the metal cover over the empty expansion slot you've chosen. Remove your sound card from its protective packaging. When you open this bag, carefully grab the card by its metal bracket and edges. Do not touch any of the components on the card. Any static electricity you may transmit can damage the card. And do not touch the gold edge connectors. You may want to invest in a grounding wrist strap, which continually drains you of static build-up as you work on your computer.

You may have to set jumpers or DIP switches to configure your sound card to work best with your computer, although most newer Plug and Play (PnP) sound cards don't have any jumpers or switches and are set by software instead. For example, you may want to turn off your sound card's joystick port because your joystick is already connected elsewhere to your PC. See the instructions that came with your sound card.

If an internal CD-ROM drive is to be connected to the sound card, attach its cables. Attach your CD-ROM's striped ribbon cable to your sound card, placing the red edge of the CD-ROM cable on the side of the connector on which "0" or "1" is printed. The cable must be placed this way for the CD-ROM drive to work.

The CD-ROM drive also may have an audio cable. Connect this cable to the audio connector on the sound card. This connector is keyed so that you can't insert it improperly. Note that there is no true standard for this audio cable, so be sure that you get the right one that matches your drive and sound card.

Next, insert the card in the edge connector. First touch a metal object, such as the inside of the computer's cover, to drain yourself of static electricity. Then, holding the card by its metal bracket and edges, place it in the expansion slot. Attach the screw to hold the expansion card and then reassemble your computer.

You can connect small speakers to the speaker jack. 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 may 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.

Using Your Stereo Instead of Speakers

Another alternative is to patch your sound card into your stereo system for greatly amplified sound. 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-inch phono plugs, which require an adapter when connecting to your stereo system. From Radio Shack, for example, you can purchase an audio cable that provides a stereo 1/8-inch miniplug on one end and a phono plug on the other (Cat. No. 42-2481A).

Make sure that you get stereo, not mono, plugs, unless your sound card supports mono only. To ensure that you have enough cable to reach from the back of your PC to your stereo system, get a six-foot long cable.

Hooking up your stereo to a sound card is simply a matter of sliding the plugs into jacks. If your sound card gives you a choice of outputs--speaker/headphone and stereo line out--choose the stereo line out jack for the connection. Choosing it 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.

Connect this output 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 mini- plug 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 sound card 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 may become distorted.

Tricks for Using the Tape Monitor Circuit of Your Stereo
Your receiver is probably equipped with something called a tape monitor. This outputs the sound coming from the tuner, tape, or CD to the tape out port on the back, and then expects the sound to come back in on the tape in port. These ports, in conjunction with the line in and line out ports on your sound card, allow you to play computer sound and the radio through the same set of speakers.
Here's how you do it:
1. Turn off the tape monitor circuit on your receiver.

2. Turn down all of the controls on the sound card's mixer application.

3. Connect the receiver's tape out ports to the sound card's line in port.

4. Connect the sound card's line out port to the receiver's tape in ports.

5. Turn on the receiver, select some music, and set the volume to a medium level.

6. Turn on the tape monitor circuit.

7. Slowly adjust the line in and main out sliders in the sound card mixer application until the sound level is about the same as before.

8. Disengage and reengage the tape monitor circuit while adjusting the output of the sound card so that the sound level is the same, whether the tape monitor circuit is engaged or not.

9. Start playing a WAV file.

10. Slowly adjust up the volume slider for the WAV file in the sound card's mixer application until it plays at a level (slightly above, or below the receiver) that is comfortable.

Now you can get sounds from your computer, as well as the radio, through the receiver's speakers.

Troubleshooting Sound Card Problems

To install a sound card, you need to select IRQ numbers, a base I/O address, or DMA channels that don't conflict with other devices. Most cards come already configured to use an otherwise idle set of ports, but problems occasionally arise. Troubleshooting may mean that you have to change board jumpers or switches, or even reconfigure your other cards. No one said life was fair.

Hardware (Resource) Conflicts

The most common problem for sound cards is that they fight with other devices installed in your PC. You may notice that your sound card simply doesn't work (no sound effects or music), repeats the same sounds over and over, or causes your PC to freeze. This situation is called a device, or hardware, conflict. What are they fighting over? Mainly the same bus signal lines or channels (called resources) used for talking to your PC. The sources of conflict in sound card installations are generally threefold:

Most sound cards include installation software that analyzes your PC and attempts to notify you should any of the standard settings be in use by other devices. Although fairly reliable, unless a device is operating during the analysis it may not always be detectable.

Table 12.2 shows the default resources used by the components on a typical Sound Blaster 16 card.

Table 12.2  Default Sound Blaster Resource Assignments

Device Interrupt I/O Ports 16-bit DMA 8-bit DMA
Audio IRQ 5 220h-233h DMA 5 DMA 1
MIDI Port -- 330h-331h -- --
FM Synthesizer -- 388h-38Bh -- --
Game Port -- 200h-207h -- --

All these resources are used by a single sound card in your system. No wonder many people have conflicts and problems with sound card installations! In reality, working out these conflicts is not all that hard, as we shall see. Most of these resources used can be changed to alternate settings, should there be conflicts with other devices, or even better, you can change the settings of the other device to eliminate the conflict. Note that some devices on the sound card like the MIDI Port, FM Synthesizer, and Game Port do not use resources like IRQs or DMA channels.

It is always best to install a sound card using the default settings where possible. This is mainly because of poorly written software that cannot work properly with alternate settings, even it they do not cause conflicts. In other words, if you are having a conflict with another type of adapter, move the settings on the other adapter rather than the sound card. Take this from experience; otherwise, you will have to explain to your five-year-old why the new Dinosaur program you just installed does not make any sounds!

If your system is PnP, you can use the Device Manager in Windows 95 to assist with the configuration of the devices in your system.

Resolving Resource Conflicts

The audio portion of a sound card has a default IRQ setting, but also supports any of several alternate interrupts. As was just stated, you should endeavor to leave the sound card at the default setting (usually IRQ 5) and change other adapters where possible.

If your sound card is set to the same IRQ as another item in your system, you may see symptoms such as skipping, jerky sound, or system lockups.

A typical sound card requires two simultaneous DMA channels to be used. These are usually split into a requirement for an 8-bit DMA as well as a 16-bit DMA channel. Most cards will use DMA 1 for 8-bit sound (Creative Labs calls this Low DMA), and DMA 5 for 16-bit sound (High DMA). The primary symptom of a DMA conflict is that you hear no sound at all.

Due to inflexibly written software, it is recommended that you stick with the default settings wherever possible in all sound card installations.

Solving Hardware Conflicts

The best way to find a hardware conflict is to locate all of the documentation for your PC and its various devices, such as a tape backup interface card, CD-ROM drive, and so on. This topic is discussed more completely in Chapter 5, "Bus Slots and I/O Cards."

The most common causes of system resource conflicts are the following:

One easy way to find which device is conflicting with your sound card is to temporarily remove all of your expansion cards except the sound card and other essential cards (such as the video card). Then add each of the cards you removed, one at a time, until your sound card no longer works. The last card you added is the troublemaker.

Having found the card that's causing the conflict, you can either switch the settings for the device that is conflicting with your sound card or change the settings of the sound card. In either case, you will have to change the IRQ, DMA, or I/O address. To do this, you must set jumpers or DIP switches, or use your sound card's setup software to change its settings.

If you are running Windows 95 and have a PnP system, you can use the built-in Device Manager to help locate and resolve conflicts.

Other Sound Card Problems

Like the common cold, sound card problems have common symptoms. Use the following sections to diagnose your problem.

No Sound

If you don't hear anything from your sound card, consider these solutions:

One-Sided Sound

If you hear sound coming from only one speaker, check out these possible causes:

Volume Is Low

If you can barely hear your sound card, try these solutions:

Scratchy Sound

Scratchy or staticy sound can be caused by several different things. Improving the sound may be as simple as rearranging things a little. The following lists suggests possible solutions to the problem of scratchy sound:

Your Computer Won't Start

If your computer won't start at all, you may not have inserted the sound card completely into its slot. Turn off the PC and then press firmly on the card until it is seated correctly.

Parity Errors or Other Lockups

Your computer may display a memory parity error message or simply "crash." This is normally caused by resource conflicts in one of the following areas:

If other devices in your system are using the same resources as your sound card, crashes, lockups, or parity errors can result. You must ensure that multiple devices in your system do not share these resources. Usually it is better to leave the sound card at its default settings and change the other devices to eliminate the conflict. Consult the documentation that comes with all of your other devices to determine which resources they use and how to change them if necessary.

Joystick Troubleshooting

If your joystick won't work, consider the following list of cures:

Other Problems

Sometimes sound problems can be difficult to solve. Due to quirks and problems with the way DMA is implemented in some motherboard chipsets, there can be problems interacting with certain cards or drivers. Sometimes altering the Chipset Setup options in your CMOS settings can resolve problems. These kinds of problems can take a lot of trial and error to solve.

The PC "standard" is based loosely on the cooperation among a handful of companies. Something as simple as one vendor's BIOS or motherboard design can make the standard nonstandard.

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