Relationship analysis of speech communication between salivary cortisol levels and personal characteristics using the Smartphone Linked Stress Measurement (SLSM)

Salivary cortisol is frequently used as a biomarker of stress. However, no study has used salivary cortisol to evaluate stress levels related to personal characteristics with a paper-based lateral flow assay (LFA) strip and a smartphone holder, and a smartphone at the same time during simulated speech communication. In this paper, we investigated variations in levels of salivary cortisol, communication apprehension, and the effects of self-efficacy via the Smartphone Linked Stress Measurement (SLSM) that we have recently reported. Saliva samples were collected by 48 participants (30 male and 18 female) at three moments: immediately before public speaking (basal measurement), immediately after public speaking (speech measurement), and forty minutes after taking a rest (relaxed measurement). Results from the questionnaire showed that salivary cortisol levels, communication apprehension, and self-efficacy were significantly correlated. Also, anxiety about speaking can raise their stress levels during their speeches, as reflected in their increased cortisol levels. Therefore, this study establishes the effects of self-efficacy on communication apprehension and salivary cortisol.