Editor's Note: This Manuscript was accepted for publication February 15, 2008.
Onset and Offset Phonation Threshold Flow in Excised Canine Larynges†
Version of Record online: 2 JAN 2009
Copyright © 2008 The Triological Society
Volume 118, Issue 7, pages 1313–1317, July 2008
How to Cite
Regner, M. F., Tao, C., Zhuang, P. and Jiang, J. J. (2008), Onset and Offset Phonation Threshold Flow in Excised Canine Larynges. The Laryngoscope, 118: 1313–1317. doi: 10.1097/MLG.0b013e31816e2ec7
- Issue online: 2 JAN 2009
- Version of Record online: 2 JAN 2009
- Phonation threshold flow;
- phonation threshold pressure;
- excised larynx;
Objectives/Hypothesis: In this study, we examined the hypothesis that the minimum flow required for phonation onset, the onset phonation threshold flow (PTF), is greater than the minimum flow to sustain phonation, the offset PTF. We also explored the hypothesis that the ratio of these two (PTF offset divided by PTF onset) falls within [0.707, 1.0].
Study Design: This was a methodology study to measure onset and offset PTFs in 10 excised canine larynges; their ratio (PTF offset divided by PTF onset) was predicted to fall in a specific domain.
Methods: The onset and offset PTF and phonation threshold pressure (PTP) values were observed using 10 excised canine larynges mounted on a bench apparatus. The subglottal flow was increased until phonation was observed, and then decreased until phonation ceased; airflow and pressure measurements at critical conditions of phonation were observed as the PTF and PTP. Larynges with elongated vocal folds were then tested to observe PTF and determine if the hypothesis was observed in pathologic-like larynges.
Results: The offset PTF was always less than the onset PTF (P ≪ .0001) and 80.0% of the observed onset-offset PTF ratios were bound by [0.707, 1.0].
Conclusions: PTF onset or offset could be a useful diagnostic parameter of the voice, particularly when used in conjunction with PTP to describe laryngeal resistance and aerodynamic power. Further exploration of the relationship between onset and offset PTF values could augment clinical diagnostic ability and advance current theories on the physics of phonation.