Not long ago, a quadriplegic at the Veterans Administration Prosthetics Center in New York City moved his motorized wheelchair and its mechanical arms using only his voice. It was a successful test of a device Marvin Herscher and Phillips Scott hope will be in full production by 1985. Their company, Threshold Technology of Delran, N.J., is a pioneer in the field of voice recognition equipment.

"The machine can be trained to understand a person's words in any language, or even grunts, so long as the grunts mean the same thing each time," says Scott, who directed the project to develop the device. Backed by venture capital from Time Inc., Xerox, and Siemens Corp., Threshold Technology has developed other voice recognition equipment that can recognize a speaker's voice even if it's hoarse from a cold. Some of the machines can even talk back. Using micro-chip processes, the device used by quadriplegics will be about the size of a large file card and will cost between $100 and $500. The price tag for larger machines that the company currently manufactures, says Scott, is between $2,000 and $15,000. He predicts that the voice recognition equipment business will grow into a multimillion-dollar industry. Threshold Technology, already a publicly owned company, plans to be in the thick of it.