Improvement of balance in young adults by a sound component at 100 Hz in music

Abstract

About 80% of young people use personal listening devices (PLDs) including MP3 players to listen to music, which consists of sound components with various frequencies. Previous studies showed that exposure to noise of high intensities affected balance in humans. However, there is no information about a frequency-dependent effect of sound components in music from a PLD on balance in young people. In this study, we determined the associations between sound component levels (dB) at 100, 1000 and 4000 Hz in music from a portable listening device (PLD) and balance objectively determined by posturography in young adults (n = 110). We divided the subjects into two groups (low and high exposure groups) based on cut-off values of sound component levels at each frequency using receiver operating characteristic (ROC) curves. Balance in the high exposure group (≥46.6 dB) at 100 Hz was significantly better than that in low exposure group in logistic regression models adjusted for sex, BMI, smoking status and alcohol intake, while there were no significant associations at 1000 and 4000 Hz. Thus, this study demonstrated for the first time that the sound component at 100 Hz with more than 46.6 dB in music improved balance in young adults.

Figure 1

Associations of balance with confounding factors including sex, BMI, smoking and alcohol. Track lengths (left box plots) and surface areas (right box plots) recorded with eyes open (open) and eyes closed (closed) in the male group (M; n = 52) and female group (F; n = 58) (A), in the underweight group (Under; n = 16), normal weight group (Normal; n = 83) and overweight weight group (Over; n = 11) (B), in the non-smokers (No; n = 96) and smokers (Yes; n = 14), in the low alcohol consumption group (Low; n = 35), middle alcohol consumption group (Mid; n = 39) and high alcohol consumption group (High; n = 36) (D) are displayed. Cut-off values of BMI (B) and alcohol intake (D) are shown in Table 1. Significant differences (*p < 0.05) were analyzed by the Mann-Whitney U test (A,C) and Kruskal-Wallis H test (C,D).

Figure 2

Associations of balance with sound levels at different frequencies output from the PLD. Track lengths (left box plots) and surface areas (right box plots) recorded with eyes open (open) and eyes closed (closed) in the low exposure group (L) and high exposure group (H) at 100 Hz (A), 1000 Hz (B) and 4000 Hz (C) of sound output from the PLD are presented. Cut-off values of sound levels at different frequencies are shown in Table 2. Significant differences (*p < 0.05, **p < 0.01) were analyzed by the Mann-Whitney U test.