Phonetic Description of Disguise through Pitch Modulation: A Pilot Study

Abstract

In traditional typologies, disguise strategies involving the increase or decrease of fundamental frequency (F₀) are typically classified as modifications of the glottal source. However, this categorization overlooks the fact that voice disguise is, in essence, a form of voice quality alteration. According to the phonetic model proposed by Laver (1980), voice quality is not limited to the vibration of the vocal folds but results from an integrated set of phonatory, articulatory, and muscular tension adjustments — known as settings — that systematically shape an individual's vocal profile in both the short and long term. The aim of this study is to investigate the articulatory adjustments involved in this type of disguise in order to describe it phonetically within the theoretical framework of voice quality. To quantify these settings, two primary metrics were adopted: the estimated vocal tract length (VTLe) and the area of the vowel space.

Keywords

Disfarce; Qualidade de Voz; Settings articulatórios; Fonética Forense; Física da Fala
Voice Disguise; Voice Quality; Articulatory Settings; Forensic Phonetics; Physics of Speech
Disfraz de Voz; Calidad de Voz ; Ajustes Articulatorios; Fonética Forense; Física del Habla

References

  1. H.J. Künzel. Effects of voice disguise on speaking fundamental frequency. The International Journal of Speech, Language and the Law 7(2): 149-179 (2000).
  2. J. Clark; P. Foulkes. Identification of voices in electronically disguised speech. The International Journal of Speech, Language and the Law 14(2): 195-221 (2008).
  3. J. Laver. The Phonetic Description of Voice Quality. Cambridge University Press, Cambridge (1980).
  4. F. McGehee. The reliability of the identification of the human voice. The Journal of General Psychology 17(2): 249-271 (1937).
  5. A. Hirson; M. Duckworth. Glottal fry and voice disguise: a case study in forensic phonetics. Journal of Biomedical Engineering 15(3): 193-200 (1993).
  6. H. Hollien; W. Majewski; P.A. Hollien. Perceptual identification of voices under normal, stress, and disguised speaking conditions. The Journal of the Acoustical Society of America 56(S1): S53-S53 (1974).
  7. I. Wagner; O. Köster. Perceptual recognition of familiar voices using falsetto as a type of voice disguise. Proceedings of the 14th International Congress of Phonetic Sciences: 1381-1384 (1999).
  8. W. Koenig. Visual spectrography. Journal of the Acoustical Society of America 18: 19-49 (1946).
  9. R.K. Potter; G.G. Kopp; H.C. Green. Visible Speech. D. Van Nostrand Company, New York (1947).
  10. L.G. Kersta. Voiceprint identification. Nature 196: 1253-1257 (1962).
  11. W. Endres; W. Bambach; G. Flösser. Voice spectrograms as a function of speaker and phonetic context. Phonetica 23(2): 48-65 (1971).
  12. A.R. Reich; K.L. Moll; J.F. Curtis. Effects of selected vocal disguises upon spectrographic speaker identification. The Journal of the Acoustical Society of America 60(4): 919-925 (1976).
  13. P. Rose; R. Simmons. The acoustic characteristics of speaker disguise. Proceedings of the International Conference on Forensic Phonetics (1996).
  14. J.C. Cavalcanti; A. Eriksson; P.A. Barbosa; S. Madureira. Revisiting the speaker discriminatory power of vowel formant frequencies under a likelihood ratio-based paradigm: The case of mismatched speaking styles. PLOS ONE 19(12): e0311363 (2024).
  15. J.C. Cavalcanti; A. Eriksson; P.A. Barbosa. On the speaker discriminatory power asymmetry regarding acoustic-phonetic parameters and the impact of speaking style. Frontiers in Psychology 14: 1101187 (2023).
  16. J.C. Cavalcanti; A. Eriksson; P.A. Barbosa. Acoustic analysis of vowel formant frequencies in genetically-related and non-genetically related speakers with implications for forensic speaker comparison. PLOS ONE 16(2): e0246645 (2021).
  17. Z. Zhang; Z.-H. Tan. An evaluation of disguised speech on speaker recognition performance. Proceedings of the 9th International Conference on Signal Processing. IEEE (2008).
  18. H.J. Künzel; J. González-Rodríguez; J. Ortega-García. Automatic speaker recognition under voice disguise. Proceedings of the International Conference on Acoustics, Speech, and Signal Processing (ICASSP) (2004).
  19. J.H.L. Hansen; T. Hasan. Speaker recognition by machines and humans: A tutorial review. IEEE Signal Processing Magazine 32(6): 74-99 (2015).
  20. G.S. Morrison; E. Enzinger; C. Zhang. Forensic speech science. In: I. Freckelton; H. Selby (Eds.). Expert Evidence, Ch. 99. Thomson Reuters, Sydney, Australia (2018).
  21. R. Rodman; M. Powell. Computer recognition of speakers who disguise their voice. Proceedings of the International Conference on Signal Processing Applications and Technology (ICSPAT2000) (2000).
  22. F. Nolan. The Phonetic Bases of Speaker Recognition. Cambridge University Press, Cambridge (1983).
  23. W. Labov. Some principles of linguistic methodology. Language in Society 1(1): 97-120 (1972).
  24. H. Masthoff. A report on a voice disguise experiment. The International Journal of Speech, Language and the Law 3(1): 160-167 (1996).
  25. P. Foulkes. Current trends in British sociophonetics. University of Pennsylvania Working Papers in Linguistics 8(3): 75-86 (2002).
  26. R.J. Podesva. Phonation type as a stylistic variable: The use of falsetto in constructing a persona. Journal of Sociolinguistics 11(4): 478-504 (2007).
  27. D. Abercrombie. Elements of General Phonetics. Edinburgh University Press, Edinburgh (1967).
  28. J. Kreiman; D. Sidtis. Foundations of Voice Studies: An Interdisciplinary Approach to Voice Production and Perception. Wiley-Blackwell, Malden (2011).
  29. J.M. Beck. Perceptual analysis of voice quality: the place of vocal profile analysis. In: A Figure of Speech: 285-322. Routledge (2014).
  30. J. Laver. Voice Quality and Indexical Information. British Journal of Disorders of Communication 3(1): 43-54 (1968).
  31. E. San Segundo et al. Voice quality analysis in forensic voice comparison: developing the vocal profile analysis scheme. International Association of Forensic Phonetics and Acoustics (IAFPA), York: 24-27 (2016).
  32. H.M. Kaplan. Anatomy and Physiology of Speech. McGraw-Hill, New York (1960).
  33. C.G. Van Riper; J.V. Irwin. Voice and Articulation. Prentice-Hall, Englewood Cliffs, NJ (1958).
  34. B.E.F. Lindblom; J.E.F. Sundberg. Acoustical consequences of lip, tongue, jaw, and larynx movement. The Journal of the Acoustical Society of America 50(4B): 1166-1179 (1971).
  35. K.N. Stevens. Acoustic Phonetics. MIT Press (2000).
  36. P.M. Morse. Vibration and Sound. 2nd ed. McGraw-Hill Book Company, New York (1948).
  37. R.D. Kent; C. Read. Acoustic Analysis of Speech. 2nd ed. Singular Publishing Group, San Diego (2000).
  38. G. Fant. Acoustic Theory of Speech Production: With Calculations Based on X-ray Studies of Russian Articulations. Walter de Gruyter (1971).
  39. K.N. Stevens. Sources of inter- and intra-speaker variability in the acoustic properties of speech sounds. In: A. Rigault; R. Charbonneau (Eds.). Actes du Septième Congrès International des Sciences Phonétiques: 206-232. De Gruyter Mouton, Berlin/Boston (1972).
  40. K.N. Stevens; A.S. House. Perturbation of vowel articulations by consonantal context: An acoustical study. Journal of Speech and Hearing Research 6(2): 111-128 (1963).
  41. A. Paige; V. Zue. Calculation of vocal tract length. IEEE Transactions on Audio and Electroacoustics 18(3): 268-270 (1970). DOI: 10.1109/TAU.1970.1162113.
  42. F. Clermont. Advances in acoustic modeling of vocal tract dynamics. Actes du Colloque de Phonétique Expérimentale. Presses Universitaires du Midi, Toulouse (2007).
  43. F. Clermont; P. Mokhtari. Analysis and interpretation of vocal tract length estimates in speech. Speech Communication 25(1-3): 185-199 (1998).
  44. F. Clermont. Acoustic modeling of the vocal tract: theoretical foundations and applications. Proceedings of the International Conference on Speech Science (2002).
  45. P. Mokhtari; F. Clermont. New perspectives on linear-prediction modelling of the vocal tract: Uniqueness, formant-dependence and shape parameterisation. Proceedings of the Eighth Australian International Conference on Speech Science and Technology: 478-483 (2000).
  46. P.A. Barbosa. Conhecendo melhor a prosódia: aspectos teóricos e metodológicos daquilo que molda nossa enunciação. Revista de Estudos da Linguagem 20(1): 11-27 (2012).
  47. P.A. Barbosa; S. Madureira. Manual de Fonética Acústica Experimental: Aplicações a Dados do Português. Cortez, São Paulo (2023).
  48. J. Hao. Cross-racial Studies of Human Vocal Tract Dimensions and Formant Structures. Ph.D. Thesis, Ohio University (2002).
  49. S.A. Xue; G.J.P. Hao; R. Mayo. Volumetric measurements of vocal tracts for male speakers from different races. Clinical Linguistics & Phonetics 20(9): 691-702 (2006).
  50. W.T. Fitch. Vocal tract length and formant frequency dispersion correlate with body size in rhesus macaques. The Journal of the Acoustical Society of America 102(2): 1213-1222 (1997).
  51. F. Nolan. Speaker recognition and forensic phonetics. In: W.J. Hardcastle; J. Laver (Eds.). The Handbook of Phonetic Sciences. Blackwell, Oxford (1997).
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Author(s)

  • Albuquerque da Silva,

    • Albuquerque da Silva

    Universidade de São Paulo

    Foneticista Forense do Instituto de Criminalística de São Paulo

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