Voice Changes in Real Speaking Situations During a Day, With and Without Vocal Loading: Assessing Call Center Operators

Abstract

Occupational-related vocal load is an increasing global problem with adverse personal and economic implications. We examined voice changes in real speaking situations during a single day, with and without vocal loading, aiming to identify an objective acoustic index for vocal load over a day. Call center operators (CCOs, n=27) and age- and gender-matched students (n=25) were recorded at the beginning and at the end of a day, with (CCOs) and without (students) vocal load. Speaking and reading voice samples were analyzed for fundamental frequency (F0), sound pressure level (SPL), and their variance (F0 coefficient of variation [F0 CV], SPL CV). The impact of lifestyle habits on voice changes was also estimated. The main findings revealed an interaction, with F0 rise at the end of the day for the students but not for the CCOs. We suggest that F0 rise is a typical phenomenon of a day of normal vocal use, whereas vocal loading interferes with this mechanism. In addition, different lifestyle profiles of CCOs and controls were observed, as the CCOs reported higher incidence of dehydrating behaviors (eg, smoking, caffeine). Yet, this profile was not linked with voice changes. In sum, we suggest that F0 rise over a day can potentially serve as an index for typical voice use. Its lack thereof can hint on consequent voice symptoms and complaints.