The conversion of spoken words into computer text. Speech is first digitized and then matched against a dictionary of coded waveforms. The matches are converted into text as if the words were typed on the keyboard.

Speaker-dependent systems require that users enunciate samples into the system in order to tune it to their individual voices. Speaker-independent systems do not require tuning and can recognize limited vocabularies such as numeric digits and a handful of words. For example, such systems have replaced human operators for telephone services such as collect calls and credit card calls.

Three Types of Voice Recognition
"Command" systems recognize a few hundred words and eliminate using the mouse or keyboard for repetitive commands. This is the least taxing on the computer. "Discrete voice" recognition systems are used for dictation, but require a pause between each word. "Continuous voice" recognition understands natural speech without pauses and is the most process intensive. Speaker-independent continuous systems that can handle large vocabularies are expected to become mainstream. Contrast with speaker recognition.