Phonation Instability Flow in Excised Canine Larynges

• Published in: Journal of voice Vol. 26; no. 3; pp. 280 - 284
• Main Authors: Hoffman, Matthew R, Rieves, Adam L, Budde, Adam J, Surender, Ketan, Zhang, Yu, Jiang, Jack J
• Format: Journal Article
• Language: English
• Published: United States Mosby, Inc 01-05-2012; Elsevier Science Ltd
• Subjects: Animals; Biomechanical Phenomena; Dogs; Excised larynx; Larynx - physiology; Larynx - surgery; Medical Disorders; Otolaryngology; Phonation; Phonation flow range; Phonation instability flow; Phonation instability pressure; Phonation threshold flow; Pressure; Rheology; Sound Spectrography; Subglottal pressure; Time Factors; Vibration; Vocal cords; Vocalization, Animal; Voice; Excised larynx; Phonation threshold flow; Subglottal pressure; Phonation instability pressure; Phonation instability flow; Phonation flow range
• ISSN: 0892-1997; 1873-4588; 1557-8658
• DOI: 10.1016/j.jvoice.2011.03.007

Summary Objective Disordered voices are often associated with abnormal changes in aerodynamic parameters of subglottal pressure (Ps ) and airflow. Phonation instability pressure (PIP) has been previously proposed to evaluate Ps at the onset of chaotic phonation. We propose the concept of and measure phonation instability flow (PIF), the airflow at which phonation becomes chaotic. Phonation flow range (PFR), PIF minus phonation threshold flow (PTF), is proposed to assess the range over which normal vocal fold vibration occurs. Study Design Repeated measures with each ex vivo larynx serving as its own control. Methods Pressure and airflow were measured at phonation onset and chaos onset in seven excised canine larynges under three experimental conditions: 0% elongation with no glottal gap; 20% elongation with no glottal gap; 20% elongation with a 3-mm posterior glottal gap. Paired t tests were performed to determine if experimental measurements differed between elongations (0% and 20%) or degrees of abduction (20% elongation with and without a 3-mm glottal gap). Results Both PIF and PFR were dependent on abduction but not elongation. PIP was not significantly dependent on either condition. PIF and PFR showed greater differences for abduction than either phonation threshold pressure (PTP) or PTF. Conclusions PIF and PFR may be useful parameters in the experimental or clinical settings, particularly when evaluating disorders characterized by a glottal gap, such as vocal fold paralysis and presbylaryngis.