Opinion ID: 1209716
Heading Depth: 1
Heading Rank: 2

Heading: The Voiceprint Technique

Text: Voiceprint analysis is a method of identification based on the comparison of graphic representations or spectrograms made of human voices. The method utilizes a machine known as a spectrograph which separates the sounds of human voices into the three component elements of time, frequency and intensity. Using a series of lines or bars, the machine plots these variables across electronically sensitive paper. The result is a spectrogram of the acoustical signal of the speaker, with the horizontal axis representing time lapse, the vertical axis indicating frequency, and the thickness of the lines disclosing the intensity of the voice. (See generally, People v. Law (1974) 40 Cal. App.3d 69, 75-76 [114 Cal. Rptr. 708]; People v. King (1968) 266 Cal. App.2d 437, 447-449 [72 Cal. Rptr. 478]; Comment, Evidence: Admissibility of Spectrographic Voice Identification (1971-1972) 56 Minn.L.Rev. 1235, 1239; Comment, The Voiceprint Dilemma: Should Voices be Seen and not Heard? (1975) 35 Md.L.Rev. 267.) Spectrograms are taken of certain cue words, such as the, me, on, is, I, and it, spoken by a known voice and an unknown voice. An examiner then visually compares the spectrograms of the same words, as spoken, and also listens to the two voices. Based upon these visual and aural comparisons, the examiner states his opinion whether or not the voices, known and unknown, are the same. (Comment, supra, 35 Md.L.Rev. at p. 270, fns. 13, 16.) Since the identification process is essentially an exercise in pattern matching, the examiner's opinion is to a large extent a subjective one based upon the relative aural similarity or dissimilarity of the two voices and visual comparison of their spectrograms. ( People v. Law, supra, at p. 79, fn. 10.) In some instances, the examiner is unable to declare positively either that there is a match or nonmatch of the sample tests, in which event no opinion is rendered. (Comment, supra, at p. 270.)