Talking Software for the Commodore 64 - Tom Jeffries
By Tom Jeffries

Talking Software for the Commodore 64

Talking games have grabbed their fair share of chart toppers this year. Our American sound expert, Tom Jeffries, went to Berkeley, in California, to talk to the freelance sound specialists who put the chat into Ghostbusters, Impossible Mission, Beach Head II, and Kennedy Approach.

The latest thing in game software today is speech synthesis. So many games on the market these days use synthesized voices that I decided to find out who was responsible for all this digital eloquence, why software companies are finding it worthwhile to include speech in their programs, and where it is all headed.

Back in the days when computers were enormous, expensive machines available only to people in large universities and corporations, the intellectual challenge of playing a game with a machine had to take the place of advanced features like graphics or sound. Computer time and memory space were far too expensive to fill up with such frills, so mainframe games were (and are) usually text-only.

Home computers changed all that. Techno-freaks being what they are, it didn't take long before people started demanding arcade-style graphics on home computers, so special chips were added and large amounts of memory were set aside just for graphics. Sound also got attention. At first outboard devices were required to create an audible output, but soon ways were found to incorporate sound capability into computers. The Apple II and IBM PC both use one of the earliest and simplest forms of onboard sound: a speaker driven by a series of on/off pulses sent by writing to a particular memory location. Programmers have created some amazingly complex sounds, including speech, using this primitive hardware.

As home computers progressed, both the graphics and sound capabilities got better and better. There has been a consistent push for greater realism in game play.

It Talks
Ghostbusters
Ghostbusters by Activision
So it won't surprise you that more and more computer games are including the sound of human (and non-human) voices. Pick up a copy of Kennedy Approach, Impossible Mission, Beach-Head II, Jump Jet or Ghostbusters and you'll see what I mean. Not only is speech synthesis being used very widely, but the quality is amazingly clear and improving all the time.

Good speech synthesis is very difficult; it didn't surprise me that most software houses have someone else do it for them. It did surprise me, however, to find out that all of the above-mentioned games except for Jump Jet had their speech provided by one company: Electronic Speech Systems of Berkeley, California. Since I only live a few miles away, it seemed like a good idea to run up there and see if I could find out the secret of their success.

ESS started in 1970 when Todd Mozer's father, Dr. Forrest Mozer, a space physicist at the University of California at Berkeley, developed a technique for speech synthesis based on playing back a digitized voice.

It had been assumed previously that this approach would use a prohibitive amount of memory, but Dr. Mozer found ways to encode the data and reduce its size as much as one hundred-fold. Other approaches rely on creating an elaborate mathematical model of the human voice, requiring either a special dedicated speech chip or a very fast, powerful (and expensive) central processor, and producing a rather mechanical sounding voice.

Dr. Mozer's algorithm keeps the natural inflections of the human voice, and in current implementations, can use any microprocessor.
 Professor Forrest Mozer
Professor Forrest Mozer

At first Dr. Mozer concentrated on hardware implementations of his ideas. His technology was used in the first talking calculator for the blind and in a speech chip produced by National Semiconductor. As the limitations of this ap proach became clear, he and his associates began to concentrate on ways to synthesize speech in software with little or no added hardware, which led to the techniques used to reproduce the incredible laugh in Ghostbusters.

Currently ESS, in addition to providing blood-curdling sounds for computer games, is producing speech synthesis products for major electronic equipment manufacturers.

They've just finished a product for AT&T that will ring you up in case of a fire or burglary at your house when you are away and tell you what the problem is; they are working with a major automobile manufacturer on a system that will tell you if your oil is low, and will tell you or your mechanic what the problem is when you break down. Wow!