A SPECTRAL ANALYSIS OF SPEECH PRE- AND POST- GLOSSECTOMY

Abstract

This study aims to use spectral analysis to explain the changes in speech caused by a glossectomy. A single patient is observed using video recordings across 30 years at four stages: before tongue cancer, after a partial glossectomy with a radial forearm free flap, after additional surgeries including removal of the flap, and without the flap in the cold, a known area of speech difficulty for the patient. Formant frequencies and consonant spectra were analyzed to quantify the changes in speech production. Results show the greatest changes in formants occur with front vowels, indicating difficulty making a constriction with the tongue tip; however, overall change in vowel formants is still minimal. Significant spectral differences were observed in the production of the sibilant fricatives /s/ and /S/, with lower spectral peaks and reduced spectral distinctiveness between the sibilant fricatives across all post-glossectomy stages, but most prominently in the cold. Other consonants are less affected, indicating the disproportionate impact a glossectomy has on speech that requires finer control of the tongue-tip. These results underscore the value of surgical techniques that preserve tongue tip mobility where possible and have further implications in post-glossectomy targeted speech therapy.