Acoustic measures have been extensively studied, in terms of their relation with laryngeal pathology, the perceptual severity of dysphonia and the outcome of interventions (surgical and conservative), as well as the other measures of vocal performance, and the results have been controversial. In the present study, patients, operated for benign laryngeal lesions with microlaryngoscopy were included. They were assessed according to the protocol, proposed by the European Laryngological Society (Dejonkere et al, 2001) with stroboscopy, perceptual analysis, voice analysis, aerodynamic measurements and subjective evaluation questionnaires, before and after the operation.
In the first part of the study, the role of the Greek version of Voice Handicap Index (VHI) was studied, in comparison with the Voice Symptom Scale (VoiSS) in terms of measuring voice surgery outcome. A statistical significant change in subscale scores, as well as in total score, was found. VHI and VoiSS correlated strongly to each other. Both VHI and VoiSS correlated with perceptual characteristics before and after the operation. Among acoustic measures, Harmonic-to-Noise Ratio (HNR) and shimmer, showed significant correlation with both VHI and VoiSS subscale and total scores, post-operatively. None of the two, however, correlated with stroboscopic, and aerodynamic measurements. VHI and VoiSS were considered useful tools in evaluating voice surgery outcome, in the Greek language.
In the second part of the study, acoustic measurements (jitter, shimmer, HNR, NHR) by two commercially available analysis programs, Praat and MDVP were compared, in terms of independent information they provide, and the influence of parameters such as gender, SPL, as well the data acquisition system. Moreover, the relationships between acoustic measurements and the other measures of vocal assessment, especially perception and VHI, were studied with correlation coefficients, as well as with Mutual Information analysis. All measurements changed significantly postoperatively, except for F0. The results were dispersed among individuals, as not all patients had pathological measurements preoperatively, neither improved in all measurements postoperatively. The two programs seemed to correlate in the majority of cases, MDVP measuring higher values. Noise measures from Praat were observed to correlate the most with perceptual parameters (GRBAS scale). MI analysis, revealed in many cases nonlinear relationships between the pairs of measures analyzed.
Acoustic voice analysis was proven to a useful outcome measure of microlaryngoscopy, as part of the multidimensional voice assessment protocol
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