The aim of this study, conducted in partnership with the Department of Surgical Oncology, Centre Paul Strauss in Strasbourg, is to assess the consequences of thyroid surgery on the voice of patients, in order to identify the various perturbations caused by this surgery, and also to reveal possible compensatory strategies or readjustments that the patient may develop, alone or with speech therapy; this is a longitudinal study. The assessment was based on the analysis of acoustic signals, from which a large amount of cues related to voice quality, but also to articulatory behaviour of speakers was extracted. Production of sustained vowels allowed carrying out two spectral studies. The spatiotemporal study was made possible through the analysis of nonsense words, and more specifically through VCV sequences. We conducted three experiments on the acoustic level. The first experiment deals with the spectral characteristics of the voice of patients who underwent thyroidectomy, with no laryngeal paralysis. The second study was conducted based on spectral characteristics of the voice of speakers with laryngeal post-thyroidectomy paralysis. Our final experiment was to study spatio-temporal characteristics of the voice of speakers who underwent thyroidectomy, with laryngeal paralysis. Articulatory interpretations, made from the acoustic data, reveal perturbations of gestures on both the glottal and supraglottal levels, with readjustment strategies varying according to patients. The concept of a "target" as a control space for execution of possible articulatory and acoustic entities, which are perceptually acceptable, seems particularly relevant in this study, since disordered speakers reorganize their productions according to their own physiological and anatomical constraints, caused by the disorder.
Perturbation of speech production as a result of thyroid gland surgery