Factors Influencing Teachers' Experience of Vocal Fatigue and Classroom Voice Amplification.

The study was a one-time survey, so it cannot show whether amplification caused vocal fatigue or whether teachers with vocal fatigue were more likely to use amplification. All measures were self-reported, including vocal fatigue and amplification use, so recall bias and under-reporting are possible. Teachers were recruited through convenience sampling, and several of roughly 1,200 started surveys did not complete enough to be included. The researchers filled in some missing answers using a statistical method, with some variables missing 10% of responses. The study did not test whether amplification reduced vocal fatigue, and it did not collect objective voice measures or classroom noise data. The recovery factor of the Vocal Fatigue Index was reversed in this study, so its scores are not directly comparable to the original VFI paper. Less than 40% of teachers had access to amplification, so the findings may not reflect teachers with adequate access or properly fitted systems.

Do not conclude that classroom amplification causes vocal fatigue. The survey found a link between more frequent use and higher fatigue scores, but teachers may have started using amplification because they already had voice problems.