Comparisons of urge-to-cough during various external vibrations. (A) Dose–response relationship of urge-to-cough as a function of citric acid concentrations. Data are mean ±standard errors (SE). The comparisons among curves, calculated by two-way repeated ANOVA, failed to reveal significant difference. The comparison between curves not indicating p values means no significant difference. (B) Urge-to-cough sensitivities are expressed as the log transformation of the lowest concentration of citric acid that elicited urge-to-cough (Cu). Closed circles and error bars indicate the mean value and SE in each group, respectively. P values were calculated by one-way ANOVA with Fisher’s PLSD post hoc. Comparisons between the groups not indicating p value mean no significant difference.