Head Over Heels: The Effects of Three Heel Heights on Postural and Acoustical Measures of University Female Voice Majors, and Measured Relationships Between Heel Height, Pitch, Vowel, Behavior, Head Position, Jaw Opening, and dB SPL

Abstract

The purpose of this study was (a) to determine the effects, if any, of 3 simulated heel height conditions (0.0 in., 1.5 in., 3.0 in.) on postural (head position, jaw opening) and acoustical (LTAS, dB SPL) measures of university female voice majors (N = 35) in 2 conditions (silence, singing sustained [ɑ] and [i] vowels on each pitch of a 2-octave A-major scale [A3-A5]), and then to (b) assess selected relationships between heel height behavior conditions, postural data, and acoustical data. Primary findings included significant main effects for heel height, pitch, vowel, behavior, and formant location conditions on participants’ postural and acoustical data. As heel height increased, participants significantly (a) decreased head position angle 1 and angle 2, (b) decreased jaw opening, (c) decreased LTAS mean signal energy, and (d) increased amplitude (dB SPL). As pitch ascended, participants, on average, significantly (a) increased head position angle 1 and angle 2, (b) increased jaw opening, and (c) increased amplitude (dB SPL). When singing the open vowel of [ɑ] compared to the closed vowel of [i], participants significantly (a) increased head position angle 1 and angle 2, (b) increased jaw opening, and (c) increased amplitude (dB SPL). From silent to singing behaviors, participants significantly (a) increased head position angle 1 and angle 2, and (b) increased jaw opening. Participants significantly increased head position angle 1, head position angle 2, and jaw opening when singing pitches above the point where the fundamental frequency (F0) would equal or exceed the first format frequency (F1) of the low pitch of A3. Data analyses yielded multiple significant interactions between independent variables and indicated significant, moderate to strong, positive relationships between (a) pitch and dB SPL, (b) pitch and jaw opening, (c) jaw opening and behavior, (d) jaw opening and head position angle 1, and (e) jaw opening and dB SPL, and significant, moderate, negative correlations between (a) jaw opening and vowel, and (b) heel height and head position angle 1. Results were discussed in terms of general outcomes, considerations for vocal music education and voice research, limitations of the study, and suggestions for future investigations.