Bibliometric analysis, systematic review of literature, and meta-analysis on the effect of amplification on voice production among teachers

Background: Teaching is identified as a high-risk profession for developing voice disorders due to the significant vocal demands placed on educators. This can lead to symptoms such as vocal fatigue, adversely affecting their quality of life. One common intervention is the provision of voice amplification systems, which have been reported to reduce vocal strain by enabling teachers to speak at lower volumes, thereby potentially improving voice quality and minimizing vocal fold damage. Despite these benefits, various factors such as adoption rates, technical issues, and the need for proper use and training can influence the effectiveness of these systems. This study systematically reviews the literature and conducts a meta-analysis to determine the impact of voice amplification on teachers' vocal function. Methods: The results reported in this manuscript are based on a bibliometric analysis and systematic literature review using seven databases, selecting 20 relevant publications from an initial pool of 462, and performing a meta-analysis to compare vocal metrics with and without amplification. Results: The meta-analysis indicated that voice amplification systems tend to positively affect fundamental frequency, sound pressure level (SPL), and phonation time percentage; however, these effects were not statistically significant. The analysis also suggests no significant publication bias, though the quality of the included publications varied: 15 % were rated as strong, 25 % as moderate, and 60 % as weak. Conclusion and Recommendations: The study concludes that voice amplification systems show potential benefits for teachers' vocal health. However, their implementation should be part of a broader strategy that includes education, training, and regular monitoring to maximize their effectiveness.