Characteristics of speech production in patients with T1 glottic cancer who underwent laser cordectomy or radiotherapy

Purpose: Laser cordectomy (LC) or radiotherapy (RT) is often recommended in the early stage of laryngeal cancer. We conducted perceptual and acoustic analysis to compare sustained vowel and stop consonants since there is no article evaluating both the sustained vowel and stop consonants. Eventually, we might determine which management is superior in terms of speech production. Subjects and methods: A total of 28 patients who underwent LC and RT for early T1 glottic cancer were selected. The sustained vowel /a/ and bilabial stop consonants were used to assess the perceptual scores. The fundamental frequency (F_o), jitter, shimmer and noise-to-harmonic ratio (NHR) levels for sustained vowels were evaluated. Voice onset time (VOT), vowel duration (VD) and closure duration of the bilabial plosives were analyzed. A receiver operating characteristic curve analysis was used to evaluate significant results statistically. Results: The GRBAS and discrimination scores were not significantly different between two groups. F_o and jitter were significantly higher in the LC than RT. The cut-off value was statistically higher in the LC group and statistically lower in the RT group. The VOT was significantly longer in the LC than RT. The cut-off value of the /pipida/ VOT was statistically longer in the LC group and statistically shorter in the RT group. Conclusions: The differences may have been due to muscular fibrosis after RT. Movements of vocal cords with fibrosis were sluggish, when impulsion developed to pronounce the initial /p/ sound, so the VOT was shortened and the VD was longer after RT.