Preliminary Investigation of Four Voice Therapy Concepts in a Single-Subject Design with Four Professional Teachers.
Elizabeth U Grillo
PMID 40340177WHAT IT FOUND
In four teachers, both voice therapy models raised recorded pitch and lowered self-rated roughness and strain, but neither clearly beat the other.
The full model trained voices for quiet, loud, and noisy teaching; the reduced model trained one voice.
Key findings
01In female teachers, both voice models produced higher fundamental frequency than before therapy, and the two models ended at similar values.
02Self-rated roughness and strain decreased after therapy regardless of which voice model was used.
03Teachers said the full model helped them get loud, talk quietly, and talk over classroom noise more than the reduced model.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only four teachers completed the comparison, and eight of the 12 enrolled teachers did not complete this study. All participants had no diagnosed voice disorder and no current voice therapy, so the results are about prevention in vocally healthy teachers, not treatment of voice disorders. The study was a preliminary single-subject design with three baseline periods, and the authors note that prior student-teacher work used 14 data collection time points over a semester. Therapy was delivered by graduate speech-language pathology students under 100% supervision from the author, so it may not reflect independent clinical delivery. Some outcomes were self-ratings and survey responses, which depend on participant perception.
The easy way to misread this
Do not read this as proof that the full model is better than the reduced model or that it treats voice disorders. Only four teachers without diagnosed voice disorders completed the study, fundamental frequency rose after both models, and both models shared the resonant voice training and bottom-up hierarchy.