Introduction :

Speaking to a computer known as voice input or speech recognition, is another form of source input. Speech recognition devices, accept the spoken word through a microphone and converts it into binary code(0s and 1s) that can be understood by the computer. Typical users were those with "busy hands," or with no access to a keyboard. Such users are changing radio frequencies in aeroplane cockpits, controlling inventory in an auto junkyard, reporting analysis of pathology slides viewed under a microscope, asking for stock-market quotations over the phone, inspecting items moving along an assembly line, and allowing physically disabled users to issue commands.

The speech recognition system "learns" the voice of the user, who speaks isolated words repeatedly. Speech recognition system, that are limited to isolated words are called discrete word systems, and users must pause between words. Continuous word systems will be able to interpret sustained speech, so user can speak normally. A key advantage of delivering input to a computer in a normal speaking pattern is ease of use.
Today, software is available to let computers take dictation from people who are willing to pause . . . briefly . . . between . . . words; the best systems are quite accurate and equivalent to typing 70 words per minute.