Introduction: The harmful effects of smoking cigarette on body organs are well documented. There are
more than 40 acoustic voice parameters and the effects of smoking cigarette on them are still studied. The
aim of this study was to examine and compare some acoustic voice parameters between smoker and non
smoker men.
Material and Methods: In this cross–sectional study, some acoustic voice parameters including;
fundamental frequency, jitter, shimmer, irregularity, contact quotient and elements of speech pattern were
compared between 2 groups of men consisting of 20 smokers and 20 non-smokers. Each parameter was
calculated using speech studio software and an electrolaryngograph.
Results: The men’s voices differed on several parameters. The mean fundamental frequency in smokers
was significantly lower (P<0.001) than this one in non-smokers. The mean jitter, shimmer and irregularity
of men who smoke were significantly higher (P<0.001) than those mean in the men who did not. The mean
silence among smokers was significantly higher (P<0.001) than that mean among nonsmokers. In contrast,
the mean of voicing in the men who smoke was significantly lower (P<0.001). No significant difference
was observed between the two groups with respect to contact quotient, nasality, and friction.
Conclusion: Fundamental frequency is the most vulnerable acoustic parameter of voice in smokers. The
higher means for jitter shimmer and irregularity of voice in men who smoke is most likely related to
epithelial changes in the vocal folds, inflammation caused by cigarette smoking, and the neurologic effects
of nicotine and other chemical materials of cigarettes. It seems that the increased time of silence during
connected speech of smokers is related to the defective quality of the closed phase of vocal cords
movement
