The aim of this study was to quantify the role of inner speech in categorical flexibility tasks. Research has shown that the suppression of inner speech in cognitive flexibility tasks leads to poorer performance by subjects. In contrast to previous studies, our objective was to offer tasks that enabled subjects to freely verbalize their reasoning, and to quantify its use. Using surface laryngeal electromyography to measure inner speech signals, we demonstrated that the more difficult the switching task, the greater the quantity of speech recruited by subjects when retaining and applying rules. Furthermore, our results show that relatively older adults (M = 50 years) tend to rely on inner speech more than younger adults (M = 25). We discuss the idea that speech acts as a support to executive functions and that it is needed to a greater extent with age due to declining executive performance.