Experimentally induced blockage of a sustained vowel by nonlinear distortion of sidetone
Harold Walter William Homann · OhioLink ETD Center (Ohio Library and Information Network) · 1963
A nn Arbor, M ichigan not "been the only alteration of sidetone tested.Tomatis^ filtered the sustained vowel of a subject rejecting certain bands of frequencies and found, upon subsequent spectrographic analysis, that those bands were in large measure also missing from the voice of the subject.g Vannier, Saumont, Labarraque, and Husson reported that phase-shifted sidetone, when presented to a subject sustaining a falsetto vowel, 7 produced phonatory blockage.Stromsta produced similar phonatory blockage by overdriving amplifiers in the feedback circuity, thus producing nonlinear distortion of the sidetone of the subject's sustained vowel.Phase-shifted sidetone was also attempted in Stromsta's study with indeterminate effects.During preliminary investigations connected with this study, the observer noted that subjects generally emitted a breathy sound as an accompaniment of phonatory blockage.Reinstitution of the sustained vowel seemed to occur at a different pitch than was true previous to blockage.Subjects commented that they felt a tendency to strain during blockage.Ihesfe comments, coupled with the noted pitch change in the immediate post-phonatory blockage situation, led ^Husson, R., "Modifications Phonatoires d'Origine Auditive et Application Physiologique et Cliniques."Bull.Acad.Natl.Med.1920:393 (1957)• (Secondary reference to an earlier work by Tomatis in 195^ at present unavailable.)g Vannier, J., Saumont, R,, Labarraque,,L., and Husson, R., "Production Experimentale de Blocages Synaptiques Recurrentiels par des Stimulations Auditives Homorythimiques avec Dephasages Reglables."Revue de Laryngologie.Bordeaux (195*0 • (From a reprint; no pagination.)7 Stromsta, C., "Experimental Blockage of Phonation by Distorted Sidetone."JSHR.2:3:296-301 (1959)* 11Husson, R., "La Vibration des Cordes Vocales (de l'horame) sans Courant d'Air et les Roles d fune Pression Sous-Glottique Eventuelle."Journal de Physiologie.k 9 ' .217-20 (1957)* 12Rubin, H. J., "The Neurochronaxic Theory of Voice Production-A Refutation."AMA Archives of Otolaryngology.71:913-20 (i960 ).^Stromsta, op.cit., pp.29^-5• respect, Wiener speaks of the breakdown of voluntary activity in terms of overloading the feedback mechanism.The encoding of the feedback information at the ears or in some neural way--station is disturbed and apparently overloads the circuity causing the motor or efferent aspect of speaking to behave in an other-than-normal fashion.Disturbance of the air-conducted sidetone may indeed produce defective neural encoding.The reported disturbance of speech when the speaker is subject to delayed, phase-shifted, nonlinearly distorted,-or fil tered sidetone may well be studied in terms of changes in the frequency of phonation.The problem under test is whether or not there is a difference between conditions of sidetone of sustained vowels in terms of their productiveness of phonatory blockage as measured in number of blocks per time unit.The effect of phonatory blockage on frequency of phonation will also be studied.It will be necessary first to attempt to induce phonatory blockage experimentally and, via appropriate statistical analysis, ascertain which alterations (nonlinear distor tion, phase shift, or filtering) or combinations of alterations of sidetone, seem to produce significant phonatory blockage. Null HypothesesThe questions under test deal with a study of types of side tone distortion, if any, that were productive of phonatory blockage.