In the everyday world, speech is our most common form of communication. But as soon as we sit down at our computers, chances are we enter a silent world where all communication is visual.

So it was quite a revolution when I gave my PC a set of vocal chords and began to listen to it talk to me.

Monologue 2.0 from First Byte in Santa Ana, Calif., (714-432-1740) is a $149 program that gives a PC the power of speech. It is an upgrade of SmoothTalker, which First Byte introduced in 1984.

Unlike digitized speech, which is essentially a digital recording of actual spoken words, Monologue creates synthesized speech by reading the text or numbers on your screen and pronouncing them according to an elaborate set of rules.

The software is memory-resident, meaning that when you start it, the program loads itself into your computer's memory and then returns control to you so that you can run other programs.

When you are ready to ask Monologue to read to you, press the "hot key" combination of Alt-T and a menu appears on the bottom line of your screen, along with a square marker in the middle of the screen. You move that marker, either with cursor keys or a mouse, to highlight the portion of the screen that you want to be read. Pressing the Enter key starts the voice.

A male or female voice is available, with either bass or treble tone. The built-in speaker in a PC serves as the voice outlet, but, frankly, it doesn't sound very good.

To show what can be expected with a better speaker, First Byte included an external speaker system for the PC in its preview package. The $80 unit is called Speech Thing, manufactured by Covox Inc. of Eugene, Ore. (503-342-1271). Other audio systems are available and supported by Monologue, such as Sound Blaster, Echo PC+, Hearsay and IBM Speech Card.

A simple connector attaches to the printer port of the computer with the printer cable then attaching to that connector. In other words, voice signals are passed out of the printer port where they are intercepted by the speaker. Is computer speech just a gimmick? Why would you want it?

Several answers come easily to mind. First, anyone who is visually handicapped would surely benefit from having the computer read back what has been typed.

This is also the case for other users. I've always had a hard time proofreading my writing from the computer screen. Either I fail to see that the words I thought I wrote aren't really there, or I fail to see extra words that are on the screen and shouldn't be. Either way, proofing while Monologue reads the text imposes a discipline that makes it more likely to catch mistakes.

The voice is understandable, much more so with the Speech Thing speaker, and has a degree of inflection, rising at the end of questions and falling at the end of sentences. But it doesn't sound like a voice for which English is a native language. There is a sing-song quality to it that is unnatural.

I couldn't hear any difference in speed or quality whether I ran it on a fast 386 computer or an old AT compatible. Word pronunciation is remarkably good. I was amazed at how well it did with a list of names, some of foreign origin.

It will not pronounce words that are written in all capital letters. It spells them instead. There is a way to help it pronounce odd words better by entering them in an exception table along with the phonetic sounds. You can fine tune the process, with Monologue pronouncing the word each time until you are satisfied. I got it to pronounce my last name quite well.

Numbers are pronounced even better than words, and are easily understood even on the PC's internal speaker, if you can get enough volume out of it. It will say numbers as hundreds, millions and thousands whether the commas are there or not.

Telephone numbers are properly enunciated a digit at a time and percents are properly pronounced if followed by a percent symbol. Decimal numbers are spoken using "point" to mark the decimal.

Spreadsheet formulas are almost noted properly. The exception is the division symbol "/", which Monologue ignores.

I can see that Monologue would be a very useful tool in proofing rows or columns of numbers entered into spreadsheets or databases. To do this, you would simply highlight a column of numbers to be checked and compare the originals as Monologue read what had been entered on the screen.

The program also can be set up to read an entire file. One way you might use this is to have Monologue read your electronic mail to you as you attend to something else on your desk.Richard O'Reilly is a Los Angeles Times staff writer. Write to Richard O'Reilly, Los Angeles Times, Times Mirror Square, Los Angeles, Calif. 90053.