Onset and offset phonation threshold flow in excised canine larynges.
OBJECTIVE
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].


METHODS
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.
Regner
Michael F
MF
Department of Surgery, Division of Otolaryngology Head and Neck Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53706, USA.
Tao
Chao
C
Zhuang
Peiyun
P
Jiang
Jack J
JJ
D000399:Air Pressure; D000818:Animals; D004285:Dogs; D007830:Larynx / Q000502:physiology*; D008962:Models, Theoretical; D010699:Phonation / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D014827:Vocal Cords / Q000502:physiology*