Muscle Activity and Aerodynamic Voice Changes at Different Body Postures: A Pilot Study

Objective: Body posture is a commonly discussed component of voice training and therapy. However, body postures, postural changes, related posturing muscle monitoring, and the potential changes in voice production (eg, glottal aerodynamic changes, acoustic differences) have been inconsistently described in the literature, leaving room for free interpretation and possible misunderstandings. The primary purpose of this pilot study was to compare the magnitude of electromyographical activation of muscles involved in phonation-breathing functions and their changes due to four standardized body postures in experienced singers. Secondly, to identify which body posture produces greater changes in aerodynamic parameters, vocal pitch, and loudness. Methods: Eight healthy adults with experience in singing voice performed a vocal task during different body postures commonly used in both voice training and therapy. A 3D-capture system was used to control and quantify the alignment of each posture. During the performances, surface electromyography (sEMG) was used to measure the muscular activity involved in the breathing/phonation and posture processes. A nonparametric Kruskal-Wallis test was used to compare the sEMG activity of phonatory muscles and aerodynamic voice variables between postures. Results: Our study did not reveal significant differences in sEMG activity, aerodynamic parameters, vocal pitch, and loudness among body postures during vocal task productions. However, the vocal pitch (in semitones) revealed significant differences in the unstable surface when compared to the upright posture, modified upright, and leaning postures. Conclusion: The body postures selected did not generate voice aerodynamic modifications of the voice nor in the levels of activation of muscles involved in the phonation-breathing process in individuals with experience in singing voice. Modifications of body posture as a tool for voice therapy should be further investigated, considering the population with voice problems and no voice training experience.