Characterization of upper esophageal sphincter pressures relative to vocal acoustics

Strength of vocal fold adduction has been hypothesized to be a critical factor influencing vocal acoustics but has been difficult to measure directly during phonation. Recent work has suggested that upper esophageal sphincter (UES) pressure, which can be easily assessed, increases with stronger vocal fold adduction, raising the possibility that UES pressure might indirectly reflect vocal fold adduction strength. However, concurrent UES pressure and vocal acoustics have not previously been examined across different vocal tasks. Doing so may offer insights into the potential use of UES pressure for relative quantification of the strength of vocal fold adduction and how this might contribute to vocal acoustics across different vocal tasks. We assessed UES pressure relative to vocal acoustics in 32 vocally healthy adults during sustained vowels, whispered sentences, and spoken sentences. Smoothed cepstral peak prominence (CPPs) and low-to-high spectral energy ratio (LHR) were derived from the acoustic signal. After controlling for resting UES pressure, age, and sex, we observed significant negative correlations between UES pressure and CPPs and a significant positive correlation between UES pressure and LHR. UES pressures were significantly higher during spoken sentences than whispered sentences and sustained vowels. Measuring UES pressure relative to vocal acoustics is a novel methodology for studying upper aerodigestive tract physiology during phonation and has the potential to enhance understanding of voice disruption in clinical populations. Clinical implications and considerations for implementation are discussed.