Once upon a time, long long ago, say 50 years, music was made by persons who operated things called musical instruments. By either blowing or banging upon something, they caused vibrations of sound.

Now, music is made by pumping commands at computers and our ears are tickled with sounds from ``instruments'' that never had a physical existence as synthesizer and MIDI devices wail away on electronic sound stages.

MIDI (Musical Instrument Digital Interface) is a standard for the way music widgets talk to computer widgets, and devices using it were once so expensive they were found only in professional recording studios.

But marching technology has made the consumer-level MIDI devices and programs better and better, and an outstanding example of this is CyberSound Studio 3.0 by InVision Interactive of Palo Alto, Calif.

CyberSound Studio 3.0 includes a well-made MIDI piano-style keyboard, a power supply and a cable to connect the works to the joystick port of a high-end PC or Mac.

High-end for the PC means at least a 133-megahertz Pentium processor, Windows 95, 16 megabytes of RAM, 16-bit audio sound card, and a 13-inch or larger monitor. Although it will run with 16 megabytes of RAM, the manufacturer suggests 24 megabytes would be better. I reviewed it on a 200-megahertz Pentium with 32 megabytes of RAM.

For the Mac, a Power PC-equipped computer running System 7.1 or higher, with the same RAM and monitor requirements as the PC. A CD-ROM drive is needed for both to install the software.

CyberSound Studio 3.0 is both a synthesizer and a sequencer, which means it can synthesize sounds, and then record and play them on up to 16 ``tracks,'' either individuallly or together.

The result is that you don't have to record or play all the components of a composition at once. My highest contribution to performance music was abandoning it when I got to college, so I began with a drum track, selected a drum sound and laid down what I knew to be a compelling rhythym.

Next was time for a bass line, so I used the keyboard for soul-stirring bass flow. Each time you record a new track and instrument, you can opt to listen to the previous tracks as you record a new one.

Soon this work of modern rock was ready for a first performance. The critical silence of the rest of my household and a pained expression on the dog suggest that I stick to writing, but the experience was fun.

The package features 128 voices and more than 1,200 instruments and sounds and allows you to edit, cut and paste your creations, which are aided by a library of existing templates.

CyberSound Studio 3.0 is available in computer retail outlets. Or you can be directed to an on-line purchase by visiting the website http://www.cybersound.com. The suggested retail price for the package is $149.95.

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Questions and comments are welcome. Send them to CompuBug, P.O. Box 626, Summit, N.J. 07901. Or e-mail via the Internet, Larry_Blasko''at''ap.org.