The process of recognizing elements of speech by analysis of the acoustic signal. Many systems may be trained to a particular operator’s voice and can build up dictionaries/vocabularies to enable faster and more accurate recognition.

Typically speech recognition is a many-stage process, starting with the digital sampling of the acoustic signal followed by some form of spectral analysis, such as linear predictive coding (LPC), cochlear modelling, etc. The next stage is to recognize the elements of speech—phonemes, groups of phonemes, and words; many systems employ hidden Markov model (HMM) algorithms, dynamic time warping (DTW), or neural networks (NN) for the recognition phase. In addition most systems utilize some knowledge of the language.

See also voice input device.