Today's digital compact disc (CD) technology relies on mirrors, lenses, and a laser beam to read music encoded in a sequence of disc pits. The digital recording process results in better sound quality as well as mobility. In addition to playing CDs on your home or car stereo or portable disc player, you even can play them from your computer's compact disc, read-only memory (CD-ROM) drive.

But what if your musical tastes lag behind technology? You probably can find a CD version of your old records. But if your record collection contains recordings that have never been digitally remastered or are currently out of print, or if you want to create compilation collections of your favorite hits, you won't be able to find an audio CD equivalent. In these situations, consider your digital alternatives.

Thanks to modern computer technology, you easily can convert analog music signals stored on conventional record platters into digital sound for computer playback. The digital audio may be stored on your hard drive as tiny pieces of data for your listening pleasure or for use in business presentations and other multimedia productions. Alternatively, you can convert the newly acquired audio data into a format for output onto your very own CD. A real bonus is that digital recordings will never degrade with playback or copying as records and magnetic tape recordings do. Whichever solution you choose, the digitizing process described below will also work for analog recordings stored on 8-track, cassette, or reel-to-reel tape.

At one time, the technology required to record digital sounds could be found only in professional recording studios or specialized commercial applications. Today, you can record digital sound right from the computer desktop. You'll need to invest some time and money in the process, but if your investment rejuvenates an old record or tape collection, it's a small price to pay. Sound recording essentials include the following items.

Sound Source.

This could be a record player, tape player, or CD player. The process of getting sound from old records and tapes into the computer is actually one of making the right connections.

"You can't plug a record turntable directly into your computer like you can a tape player," says Gerry Tschetter, consumer products marketing manager at Yamaha Corp. of America. The electrical output of a turntable has to go through an RIAA (Recording Industry Association of America) amplifier first in order to compensate for certain characteristics of the phonograph stylus and turntable, Tschetter says. This amplifier, or receiver, must have a Phono Input (two RCA jacks, one white and one red) to connect to the turntable. It must also have either a Tape Out or a line output of some sort (again characterized by red and white RCA jacks).

Windows 95's Sound Recorder utility offers no-frills recording as you can record just 60 seconds of sound at several quality levels.

An inexpensive adapter cable, with two male RCA plugs at one end and one stereo mini 3.5 mm phono plug on the other, connects the amplifier to the PC. You can find this at most computer or audiovisual stores for about $6. Insert the cable's red and white RCA plugs into the amplifier's corresponding red and white Phono Out jacks. Then insert the cable's stereo mini plug into the Line In jack at the back of your computer's sound card.

The amplifier must be positioned next to the computer for the adapter cable to make the connections. If you can't place your stereo system (turntable, amplifier, and speakers) next to the computer or can't make the right connections, you can digitize music with a microphone connected to the microphone jack on your computer's sound card. As the music plays, the mike will record the sound signals. However, even if you own a so-called "noise canceling" mike the overall quality of the recording would still be poor. A microphone is better suited for recording Windows system sounds or brief voice messages to embed in business documents.

Sound Card.

Without a sound card, most PC-based computers can only beep. With a sound card installed, computers can talk, record or play music, and produce enough sound effects to enrich any application. A sound card gets analog sound into the computer by translating the signals received from a sound source (e.g., microphone, tape recorder, or amplifier/receiver with a tape output jack).

For best results, make sure that your card features 16-bit recording and playback. Less expensive cards with only 8-bit resolution produce tinny sound. Sound resolution refers to the number of bits used to digitize a sound sample and determines how accurately a sound can be digitized. The higher a card's resolution, the truer the sound's representation in digital form. Most popular cards offer 8-bit, 12-bit, or 16-bit sampling resolutions at frequencies from 5 to 44 kilohertz (KHz).

Sound cards that record or play back with 8-bit resolution only can store a total of 256 digital values for any given sound level. This is considerably lower fidelity than cards with 16-bit resolution. A 16-bit card can manage up to 65,536 digital values for any slice of captured sound because it reproduces 256 times as much sound detail as its 8-bit counterpart.

Creative WaveStudio, the utility that ships with the popular Sound-Blaster audio hardware, creates your own sound studio as you record, play, and edit either 8-bit or 16-bit wave data.

Another factor to consider when recording sound is the sampling rate, measured in kilohertz, or thousands of cycles per second. Digitized sound is sampled sound. The sampling rate determines how often a sound board grabs and translates (digitizes) a sample of an incoming audio signal into bits and bytes the computer can store and manipulate. Sound sampled at 11KHz (11,000 bytes of data per second) is not as information-rich as sound sampled at 22.05KHz (22,050 bytes of data per second) or 44.1KHz (44,100 bytes of data per second). The higher sampling rate does a better job of capturing a sound's high-frequency content.

Most voice frequencies are on the low side (6 to 8KHz), requiring sampling rates of about 11KHz for acceptable fidelity. But to record the full range of sounds that music offers (including the higher-range frequencies of tambourines and flutes), you need a sound card with a sampling frequency of at least 40KHz. Cards capable of recording with 16-bit resolution at 44.1KHz can approximate the sound quality of CD audio. Quality varies, however, with the card's ability to deliver noise-free sounds, the speed of your computer's central processing unit (CPU), the analog and digital converter chips your sound card uses to get sound in and out of your system, and the quality of the recording microphone or sound source. Sound quality also may be affected by interference from the motherboard or cards adjacent to the audio board.

Sound storage device. As the sound card digitizes sound signals from an incoming sound source, you need a device to store them. It could be a hard drive, a removable drive such as a SyQuest or Zip drive, or a blank CD-Recordable (CD-R) drive. The medium you choose will depend in part upon what you want to do with the audio file once it's digitized. It will also depend upon the size of this file.

"If you want to create a business presentation, jazzed up with music and other special sound effects," says Rob Griffith, product manager for Adaptec's CD-Recordable Division, "you may be better off leaving the sound in .WAV format on your hard drive." A .WAV file is designed to be embedded in a presentation. Once the CPU reads the waveform from the hard drive, it's stored in random-access memory (RAM) until you click a button to play it. Then it plays immediately. Sounds stored on a CD, Griffith says, take longer to play because the head on your CD player must locate the file before playing it.

On the other hand, storing sounds on the hard drive can be costly in terms of storage space. "Audio data is huge data," Yamaha's Tschetter says, especially if the sound is recorded at higher sampling rates (44.1KHz) and larger sample sizes (16-bit). For example, you need about 10.6 megabytes (MB) of space to record just one minute of CD-quality audio. See the chart on the following page for the formulas you can use to determine how much storage space your recordings will require.

Today's multimedia computers generally come with a three or four gigabyte (GB) capacity hard drive. However, the digitized recordings from a half dozen of your favorite old records would fill up this space rather quickly. As a result, you're probably much better off transferring the digitized audio onto CDs, which can hold about 650MB of digital data or a little over an hour of stereo music.

Budget-strapped audiophiles can purchase a shareware version of Syntrillium's Cool Edit digital audio processing software and touch up any digital audio recording.

If you decide to output your digital data onto compact disc, you'll need a CD-R drive. CD-R used to be very expensive and difficult to use, Adaptec's Griffith says, but during the last year, prices have dropped dramatically while ease of use has risen exponentially. Currently, you can purchase a dual-speed (2X)-write/4X-read or 2X-write/6X-read CD-R drive for less than $800 (slightly more for an external device). You'll use the software that comes with the CD-R drive to write the digital data onto compact disc.

Recording & Editing Software.

"At the simplest level," Tschetter says, "all you are trying to do here is acquire the audio data, using the sound card to convert each track on a record into an audio .WAV file." Windows 95 comes with a Sound Recorder utility that lets you acquire this audio data. To record your own sounds in Win95, left-click the Start button, then select Programs, then Accessories, then Multimedia, and finally Sound Recorder. Sound Recorder can sample recorded sound at Radio Quality (22KHz, 8-bit mono), Telephone Quality (11KHz, 8-bit mono), CD Quality (44KHz, 16-bit stereo), or some user-defined resolution/sampling rate combination.

Before you begin recording, specify the properties you want your new sound file to have. Go to the Edit menu and choose Audio Properties, then specify the properties, such as recording quality, you want. When you're ready to record, go to the Sound Record screen and left-click the Record button, then begin playing music from your audio source. When you're done, left-click Sound Recorder's Stop button. Listen to your recording by left-clicking Sound Recorder's Seek To Start button, then left-click Play. If you like what you hear, choose Save As from the File menu, name your file, and save it.

Sound Recorder does more than simply record sound files. On its Effects menu, you'll find editing tools such as Add Echo, which creates a musical clip that sounds like it was recorded in a box, and Reverse, which plays a sound backward. If you select Mix With File from the Edit menu, you even can mix two or more recorded .WAV files so they play simultaneously. (For more on using Sound Recorder, see "Recording Sound On Your PC" in the May 1997 issue of Smart Computing.)

Sound Recorder works best with brief audio clips because the utility limits you to a 60-second recording session. To digitize music from your old records, you'll need an application that doesn't place any limits on recording time. Most sound cards come with sound recording software. For example, Creative WaveStudio, the utility that ships with the SoundBlaster audio hardware built into many computers, lets you record, play, and edit either 8-bit or 16-bit wave data. In many ways, it functions just like Sound Recorder only with more options for recording and editing .WAV files. Status readings at the bottom of the WaveStudio screen keep you informed about the length (in seconds) of the recorded audio file, its resolution and sampling rate, and the size of the file in kilobytes (KB).

Whichever sound recording software you end up using, the technique is essentially the same. Before you do any serious recording, conduct a test.

"Experiment with the line level inputs," Tschetter says. Begin by setting the recording software's volume level to the middle point, then record a sample. Next, look in the waveform monitor window of your sound recorder application. Tschetter says that if you're "overdriving" the input, you'll see peaks on the monitor exceeding the capacity of the recording. The goal is to come in as "hot" as you can without actually getting into clipping. Make sure the test includes the loudest passage in the music.

"In the ‘1812 Overture' for example," he says, "go for the cannons, the timpani, and the cymbals." If you're satisfied with the test, left-click the Record button on the sound recorder, then start the tune you want to capture. Let it play until the end. Stop recording. Play it back to ensure that it is glitch-free, then save it.

After recording a digital sample, you can touch up sound quality, eliminating any pops and clicks, removing glitches, and making it as noise-free as possible by using a sophisticated sound editor such as Sonic Foundry's Sonic Forge 4.0. This software, which offers extensive effects and digital signal processing tools, also features VCR play and record buttons to manage all sound acquisition and editing needs. Budget-strapped audiophiles who have outgrown the sound editor bundled with their sound cards can experiment with Syntrillium Software's Cool Edit digital audio processing shareware for as little as $25. It's not as powerful an editor as Sonic Forge, but it still has enough audio tools to touch up any sound recording.

After you've used all these audio tracks to secure your music and family recordings in digital format, you still may not want to throw out that old turntable or tape player. But at least you won't have to count on it to hear your favorite tunes.

by Carol S. Holzberg, Ph.D.

Cool Edit

$25 Syntrillium Software Corp. (602) 941-4327 http://www.syntrillium.com/cool.htm