Whole-body vibration as a potential method to improve phonatory function

Abstract

BACKGROUND: Whole-body vibration refers to the oscillatory movement transmitted from a mechanical vibration source to the body (Cardinale & Wakeling, 2005). Repeated exposures to whole body vibration have been shown to cause neurogenic adaption of the skeletal muscles and to facilitate muscular function improvement. Phonatory function, in terms of intensity, has been found to improve following whole-body vibration at around 10 -15 Hz when compared to vibration below 10 Hz (Yokoyama and Hoshino, 1973). This project investigated the effects of whole body vibration on the phonatory function in adults with normal voice. AIMS: The study aimed 1) to identify the vibratory frequency and intensity that produced the largest vibration of the larynx during phonation in non-dysphonic adults. 2) to determine if the vocal function, in terms of maximum frequency and intensity produced, would improve following 12 minutes of WBV. METHOD: Participants stood on a whole-body vibration machine that transmitted vibration to the body through an oscillating plate. They produced a sustained /a/ during the vibration. The frequency and intensity of the vibration were varied in four frequencies (10 Hz, 12 Hz, 15 Hz, and 20 Hz) and seven intensities (20% to 50%, in 5% intervals), thus making up 28 combinations of vibration. Two blocks of the 28 trials were randomly presented. Each trial of test vibration was accompanied by a reference (anchor) vibration (10 Hz- 25% intensity). After each trial, participants provided a perceptual rating of the amount of vibration (vibratory magnitude) felt in the laryngeal area during the test vibration compared to the reference vibration using a direct magnitude estimation scaling procedure. Participants’ voice range profiles were recorded before and after the whole-body vibration in order to identify the maximum frequency and intensity produced. Results: The participants’ perception of the vibratory magnitude was significantly higher for vibration using 15 and 20 Hz frequencies and 50% intensity when compared with the other frequencies and intensities. There was, however, no significant improvement in the maximum frequency and intensity following 12 minutes of whole-body vibration. CONCLUSION: The results suggest that the whole body vibration setting of 15-20 Hz at high intensity (50%) best targets the larynx. These specific settings will be used to in a future project that explores the use of whole body vibration as a treatment option for dysphonia. REFERENCES: Cardinale, M., & Wakeling, J. (2005). Whole body vibration exercise: are vibrations good for you? British Journal of Sports Medicine, 39, 585-589. Yokoyama, T., & Hoshino, K. (1973). Effects of whole-body vibration on speech voice intensity and maximum phonation time. Nihon Jibiinkoka Gakkai kaiho, 76 (12), 1414-1425. Retrieved from https://www.jstage.jst.go.jp/browse/jibiinkoka/-char/ja/