A new insight into post-surgical objective voice quality evaluation. Application to thyroplastic medialisation

This paper aims at providing new objective parameters and plots, easily understandable and usable by clinicians and logopaedicians, in order to assess voice quality recovering after vocal fold surgery. The proposed software tool performs presurgical and postsurgical comparison of main voice characteristics (fundamental frequency, noise, formants) by means of robust analysis tools, specifically devoted to deal with highly degraded speech signals as those under study. Specifically, we address the problem of quantifying voice quality, before and after medialization thyroplasty, for patients affected by glottis incompetence. Functional evaluation after thyroplastic medialization is commonly based on several approaches: videolaryngostroboscopy (VLS), for morphological aspects evaluation, GRBAS scale and Voice Handicap Index (VHI), relative to perceptive and subjective voice analysis respectively, and Multi-Dimensional Voice Program (MDVP), that provides objective acoustic parameters. While GRBAS has the drawback to entirely rely on perceptive evaluation of trained professionals, MDVP often fails in performing analysis of highly degraded signals, thus preventing from presurgical/postsurgical comparison in such cases. On the contrary, the new tool, being capable to deal with severely corrupted signals, always allows a complete objective analysis. The new parameters are compared to scores obtained with the GRBAS scale and to some MDVP parameters, suitably modified, showing good correlation with them. Hence, the new tool could successfully replace or integrate existing ones. With the proposed approach, deeper insight into voice recovering and its possible changes after surgery can thus be obtained and easily evaluated by the clinician.