Analog-to-digital conversion

A continuous signal is best represented as a continuous line having an amplitude value at all points in time, while a discrete signal is actually a sequence of separate amplitude values and thus is most accurately represented by separate discrete bars rather than a line. For a computer to record speech, it is necessary to convert the continuous sound wave (analog) into a discrete signal (digital) that can be stored on the computer. Two steps are involved in this analog-to-digital conversion. First, the continuous signal is chopped up in time into a sequence of 'samples'. Secondly, measuring the amplitude of the waveform at each time point corresponds to 'quantisation' (cf. quantisation noise). These two steps convert the continuous signal into a set of digits.

Link
Utrecht Lexicon of Linguistics