A device in which speech is used to input data or system commands directly into a system. Such equipment involves the use of speech recognition processes, and can replace or supplement other input devices.

Some voice input devices can recognize spoken words from a predefined vocabulary, some have to be trained for a particular speaker. When the operator utters a vocabulary item, the matching data input is displayed as characters on a screen and can then be verified by the operator. The speech recognition process depends on the comparison of each utterance with words appearing in a stored vocabulary table. The table is created or modified by using the voice input equipment together with a keyboard. A data item or system command is typed and the related spoken word is uttered, several times. The spoken word is then analysed and converted into a particular bit pattern that is stored in the vocabulary table.