Effects of smoking cigarette on some acoustic voice parameters and elements of speech pattern of male subjects

  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.