Acoustic voice analysis in different phonetic contexts after larynx radiotherapy for T1 vocal cord carcinoma

ABSTRACT

INTRODUCTION: Radiotherapy for early vocal cord carcinoma affects quality of voice. Nevertheless, most patients refer to having a high satisfaction level with their voice. The few acoustic studies on quality of voice have been performed only in prolonged vowel production, which is not a usual speech situation. The present study has been done with the aim of establishing which phonetic situations reflect a greater alteration in voice production related to irradiation. MATERIAL AND METHODS: Eighteen male patients irradiated for Tis-T1 vocal cord carcinoma and a control group of 31 non-irradiated subjects were included in a study of acoustic voice analysis. This analysis was performed one year after radiotherapy. Patients and control group voices were tape recorded in extended vowel production, oral reading of a standard paragraph, spontaneous speech and in a song. Acoustic analysis was performed by a Kay Elemetric's Computerized Speech Lab (model CSL #4300). Fundamental frequency, jitter, shimmer and harmonics-to-noise ratio were obtained in both groups. Statistical test Lin concordance coefficient and Pearson's correlation coefficient, Student's t-test and ROC curves. RESULTS: Concordance and correlation studies did not allow selection of any subgroup in acoustic parameters and different acoustic situations. Acoustic parameters had higher median values in irradiated patients. Student's t-test showed significant differences for fundamental frequency in sustained vowel production and spontaneous speech; for jitter there was statistical significance in all the acoustic situations and for shimmer in oral reading and song. Jitter showed a cut-off of 2.02% with a sensitivity of 89% and specificity of 97% in classifying irradiated and non-irradiated groups. The ROC curve for jitter correctly classified 94% of subjects into irradiated or non-irradiated groups. CONCLUSIONS: The present study showed that jitter obtained from spontaneous speech was the most relevant parameter in discriminating voice in irradiated patients by acoustic analysis. Jitter in spontaneous speech is in need of more analysis in bigger series and in more advanced stages of larynx cancer as its relevance has been demonstrated (AU)

RESUMEN

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