This study was approved by the Ethics Committee of Iran
University of Medical Sciences.
The collected data was analyzed using SPSS for Windows
software, Version 14.5. The following statistical tests were
applied for analysis of the data. T test was applied for
testing differences between the case and control groups
for quantitative parameters. Chi-square test was applied to
examine differences between the case and control groups
for categorical parameters. Association of binaural hearing
impairment with smoking habit was examined by logistic
regression. All tests applied were two-tailed, and a P value of
0.05 was considered to be statistically significant.