Effectiveness and Implementation of a One-Day Voice Preventive Program for Primary-School Teachers: A Longitudinal Study Based on Acoustic and Subjective Evaluations

A longitudinal study was conducted over 5 months on 22 primary school teachers without existing vocal disorders to assess the effectiveness of a 1-day preventive voice intervention in limiting vocal deterioration over the school year, improving vocal endurance throughout a workday, and promoting the adoption and maintenance of healthy vocal habits. A combined analysis of the variation of objective acoustic parameters [f0, Jitter, Shimmer, and harmonic to noise ratio (HNR)] throughout a workday showed that the intervention group (TEST) maintained a typical endurance profile across the school year, while the control group (CTRL) exhibited increased atypical vocal responses. Subjective assessments further supported the preventive impact, with the TEST group reporting reduced vocal discomfort and communication difficulties immediately after the intervention. Self-reported behavior frequency indicated significant progress and long-term retention of key recommendations, including "hydration," "proper anchoring before projecting voice," "giving short instructions," and distance communication strategies. Some of these recommendations also negatively correlated with vocal complaints and workday acoustic variations, suggesting their preventive relevance. These findings support the effectiveness of this 1-day voice prevention program in limiting vocal deterioration and fostering sustainable behavioral changes. This study provides new insights into selecting the most impactful strategies to further improve the applicability and effectiveness of future preventive programs.