The influence of sounds on posture control.

PURPOSE It is still not clear which parameters of sound are the most significant for body reactions and whether the way of sound reception plays a role in body control. The purpose of this study was to determine the influence of frequency, spectrum and loudness of sounds on posture control in healthy women and men. METHODS The study subjects were 29 young adults who were submitted to a 60-second standing test in the bipedal stance on the force platform (AMTI). During the tests, 3 sinusoidal sounds with various timing and 2 musical sounds (guitar and piano) of the frequency 225 Hz, 1000 Hz and 4000 Hz were applied through headphones. The centre of pressure (COP) amplitude was registered. The sway area and COP mean velocity were computed. RESULTS It was found that high frequency sounds contributed to a significant decrease of sway area values. No significant influence of low frequency sounds on posture control was observed. The influence of the sound spectrum (timbre) on posture control is limited; only the crescendo spectrum improves the body stability in the bipedal stance and not the music spectrum as guitar and piano. The loudness of sound, although extremely high, is not the cause of postural control changing in relation to lower loudness. No effect of gender was found in terms of body stability under different sound conditions. CONCLUSION Based on the results, it can be argued that, in general, in a bipedal stance in terms of stability high sound frequency improves posture control, whereas sound spectrum and intensity show a limited impact.