Statistical Analysis
Continuous variables were examined using the Shapiro–Wilk test for
normality. For continuous variables of normal distribution, the data
were presented as means ± standard deviation (SD). For the non-normal
distribution, the data were presented as medians (ranges). Spearman’s
rank correlation was used to investigate the relationship between the
percentage of noise duration and the actual monitoring time. The
p-values are two-sided. A p-value of < 0.05 was considered to
indicate statistical significance. All statistics were calculated using
R statistical software (version 2.13.0, R Foundation for Statistical
Computing, Vienna, Austria).