Purpose: This investigation compared voice performance of student teachers across an academic semester in order to examine the effect of increasing demands on their voice. Method: A repeated measures design was applied to the data analysis: all participants were tested three separate times throughout the semester. The equipments used for monitoring vocal behavior were the Ambulatory Phonation Monitor (APM), the Computerized Speech Lab (CSL), and the Phonatory Aerodynamic System (PAS), which are computer-based systems for acoustic and aerodynamic assessment of voice. Additionally, participants completed surveys related to voice usage. Results: In this study, most voice parameters of student teachers measured in a natural setting and in a controlled environment indicated changes that revealed progressive instability and noise in the course of an academic semester. Additional comparisons demonstrated differences between voice usage in the school environment and voice produced in the voice lab. Self-reported information demonstrated overall reduced awareness regarding preventive methods for voice disorders. Conclusions: Based on the results of this study, increased teaching-related voice demands associated with reduced awareness of voice production and preventive measures of voice disorders may have a detrimental impact on voice performance, leading to a risk of developing voice disorders. Learning outcomes: Participants will recognize the importance of clarifying and quantifying the relationship of vocal demands and voice performance among student teachers. (Contains 8 tables.)