Genetics of Vocal Quality Characteristics in Monozygotic Twins: A Multiparameter Approach

Published:January 31, 2005DOI:


      The main purpose of this study was to determine the vocal quality characteristics among the 45 monozygotic cotwins (MT). As the performance of the voice is related to several genetically determined anatomical and physiological factors, the authors hypothesized that the vocal characteristics and the overall vocal quality by means of the Dysphonia Severity Index (DSI) will be identical in MT. An additional objective of this study was to determine whether sex and age influence vocal similarities in MT and to compare the voice characteristics of MT with the normative data of unrelated peers. As more environmental factors influence the aging of the voice, age-related differences were expected. No sex-related differences were expected. Subjective and objective assessment techniques determined the vocal quality. No significant differences were obtained, and most comparisons resulted in significant correlation coefficients. For the acoustic parameters jitter and shimmer only, no significant correlation coefficients could be obtained. It is clear that the perceptual voice characteristics, the laryngeal aerodynamic measurements of maximum phonation time (MPT), the vocal performances, and the overall vocal quality by means of the DSI are similar in MT. These vocal characteristics are not influenced either by the subjects' age or sex and are situated within the normative range of unrelated peers. To what extent other aspects (environment, anxiety, tension, etc) might play a role in the acoustical dimensions regarding frequency and amplitude perturbation, which were in the normal range, is a subject of further research.

      Key Words

      To read this article in full you will need to make a payment


      Subscribe to Journal of Voice
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Sataloff R.T.
        Professional Voice, the Science and Art of Clinical Care.
        Singular Publishing Group, San Diego, CA1997
        • Decoster W.A.
        • Van Gysel A.
        • Vercammen J.
        • Debruyne F.
        Voice similarity in identical twins.
        Acta Oto-Rhino-Laryngologica Belg. 2001; 55: 49-55
        • Debruyne F.
        • Decoster W.
        • Van Gijsel A.
        • Vercammen J.
        Speaking fundamental frequency in monozygotic and dizygotic twins.
        J Voice. 2002; 4: 466-471
      1. Norusis, MJ. SPSS for Windows, Version 9.0. Advanced Statistics. Release 5. Chicago, IL: SPSS Inc.

        • Ryalls J.
        • Shaw H.
        • Simon M.
        Voice onset time production in older and younger female monozygotic twins.
        Folia Phoniat Logopaed. 2004; 56: 165-169
        • Wuyts F.L.
        • De Bodt M.S.
        • Molenberghs G.
        • et al.
        The dysphonia severity index: an objective measure of hoarseness based on a multi-parameter approach.
        J Speech Lang Hear Res. 2000; 43: 796-809
        • Hirano M.
        Clinical Examination of Voice.
        Springer Verlag, New York1981
        • Kay Elemetrics Corporation
        Operation Manual, CSL Computerised Speech Lab Model 4300, Software, Version 4.
        Kay Elemetrics, Lincoln Park, NJ1992
        • Heylen L.
        • Wuyts F.L.
        • Mertens F.
        • De Bodt M.
        • Pattyn J.
        • Croux C.
        • et al.
        Evaluation of the vocal performance of children using a voice range profile index.
        J Speech Lang Hear Res. 1998; 41: 232-238
        • Stemple J.C.
        • Glaze L.E.
        • Klaben B.G.
        Clinical Voice Pathology, Theory and Management.
        Singular Publishing Group, Delmar2000