SPEECH/VOICE RECOGNITION

Voice input, sometimes referred to as speech or voice recognition, allows you to enter data and issue commands to the computer with spoken words. It is an alternative to typing on a keyboard. The software has been developed to provide a fast method of writing onto a computer and can help people with a variety of disabilities. It is useful for people with physical disabilities who often find typing difficult, painful or impossible. Voice recognition software can also help those with spelling difficulties, including dyslexic users, because recognized words are always correctly spelled. Put simply, you talk to the computer and your words appear on the screen.

If you talk with pauses between your words, computers have been able to understand human speech since the early 1970s. However, no one wants to talk like that, at least for very long. The goal has always been to enable computers to understand our continuous speech. There are no pauses between our words when we talk normally.

Voice recognition promises to be the easiest method for data entry, word processing and conversational computing, since speech is the easiest, most natural means of human communication. Voice input has now become technologically and economically feasible for a variety of applications. Early voice recognition products used discrete speech recognition, where you had to pause between each spoken word. New continuous speech recognition software recognizes continuous, conversationally paced speech.

Voice recognition systems analyze and classify speech or vocal tract patterns and convert them into digital codes for entry into a computer system. For a computer to decipher the signal, it must have a digital database, or vocabulary, of words or syllables, and a speedy means of comparing this data with signals. The speech patterns are stored on the hard drive and loaded into memory when the program is run. A comparator checks these stored patterns against the output of the A/D converter.

In practice, the size of a voice-recognition program's effective vocabulary is directly related to the random access memory (RAM) capacity of the computer in which it is installed. A voice-recognition program runs many times faster if the entire vocabulary can be loaded into RAM, as compared with searching the hard drive for some of the matches. Processing speed is critical as well, because it affects how fast the computer can search the RAM for matches.

All voice-recognition systems or programs make errors. Screaming children, barking dogs, and loud external conversations can produce false

input. Much of this can be avoided only by using the system in a quiet room. There is also a problem with words that sound alike but are spelled differently and have different meanings — for example, " hear" and " here." This problem might someday be largely overcome using stored contextual information. However, this will require more RAM and faster processors than are currently available in personal computers.

Several programs are available that provide voice recognition. These systems work best on Windows 2000 and Windows XP. A number of voice recognition programs can be used with Windows, including a basic one that is supplied with Microsoft Office XP and 2003. Most special voice applications include a software CD, a microphone headset, a manual and a quick reference card. You connect the microphone to the computer, either into the soundcard (sockets on the back of a computer) or via a USB connection. Then you can begin talking using the following steps.