Aerodynamics of speech characteristics subsequent to inhaled exposure to mustard gas

Aims. Aerodynamic measurements are useful and conventional methods for acquiring clinical information about phonetic function. The purpose of this study was to analyze the aerodynamics of speech subsequent to respiratory exposure to mustard gas and compare it with normal people. Methods. This case-control research was done in 2007. 19 chemical injured male patients by mustard gas as case group and 20 normal male as control group were selected by achievable sampling method. Aerodynamic analyses were performed by ST1 Dysphonia (manufactured by G.M. Instruments Ltd). Vital capacity, phonation time, phonation volume, mean flow rate and total expired volume were measured. Vocal velocity index and phonation quotient were also calculated. The correlation between variables in two groups was studied. Data was analyzed by SPSS 11 software using independent T-test and Pearson correlation coefficient. Results. In all variables except \"mean flow rate\" a statistically significant difference was seen in compare of two groups (p<0.05). There were a significant correlation between phonation time and vital capacity and also phonation volume and phonation time, while this correlation did not exist in control group. Conclusion. Chemical injuries have failures in vital capacity, phonation time, phonation volume, vocal velocity index, total expired volume and phonation quotient.