Speaker verification, as opposed to speaker identification, is carried out by matching a sample of a person's speech with a reference version of the same text derived from prerecorded samples of the same speaker. Acceptance or rejection of the person as the claimed individual is based on the concordance of a number of acoustic parameters, for example, formant frequencies, pitch period and speech energy. The degree of match is assessed by time aligning the sample and reference utterance. Time alignment is achieved by a nonlinear process which maximizes the similarity between the sample and reference through a piece-wise linear continuous transformation of the time scale. The extent of time transformation that is required to achieve maximum similarity also influences the decision to accept or reject the identity claim.
AUTOMATIC SPEAKER VERIFICATION BY NON-LINEAR TIME ALIGNMENT OF ACOUSTIC PARAMETERS