title: A statistical analysis of cervical auscultation signals from adults with unsafe airway protection.
abstract: BACKGROUND
  Aspiration, where food or liquid is allowed to enter the larynx during a swallow, is recognized as the most clinically salient feature of oropharyngeal dysphagia. This event can lead to short-term harm via airway obstruction or more long-term effects such as pneumonia. In order to non-invasively identify this event using high resolution cervical auscultation there is a need to characterize cervical auscultation signals from subjects with dysphagia who aspirate.
  
  
  METHODS
  In this study, we collected swallowing sound and vibration data from 76 adults (50 men, 26 women, mean age 62) who underwent a routine videofluoroscopy swallowing examination. The analysis was limited to swallows of liquid with either thin (<5 cps) or viscous (≈300 cps) consistency and was divided into those with deep laryngeal penetration or aspiration (unsafe airway protection), and those with either shallow or no laryngeal penetration (safe airway protection), using a standardized scale. After calculating a selection of time, frequency, and time-frequency features for each swallow, the safe and unsafe categories were compared using Wilcoxon rank-sum statistical tests.
  
  
  RESULTS
  Our analysis found that few of our chosen features varied in magnitude between safe and unsafe swallows with thin swallows demonstrating no statistical variation. We also supported our past findings with regard to the effects of sex and the presence or absence of stroke on cervical ausculation signals, but noticed certain discrepancies with regards to bolus viscosity.
  
  
  CONCLUSIONS
  Overall, our results support the necessity of using multiple statistical features concurrently to identify laryngeal penetration of swallowed boluses in future work with high resolution cervical auscultation.
authors.affiliation: Department of Electrical and Computer Engineering, Swanson School of Engineering, University of Pittsburgh, 3700 O'Hara Street, Pittsburgh, PA, 15261, USA. jmd151@pitt.edu.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Dudik
authors.affiliation: Department of Communication Science and Disorders, School of Health and Rehabilitation Sciences, University of Pittsburgh, 4028 Forbes Tower, Pittsburgh, PA, 15260, USA. atk22@pitt.edu.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Kurosu
authors.affiliation: Department of Communication Science and Disorders, School of Health and Rehabilitation Sciences, University of Pittsburgh, 4028 Forbes Tower, Pittsburgh, PA, 15260, USA. jcoyle@pitt.edu.
authors.forename: James L
authors.initials: JL
authors.lastname: Coyle
authors.affiliation: Department of Electrical and Computer Engineering, Swanson School of Engineering, University of Pittsburgh, 3700 O'Hara Street, Pittsburgh, PA, 15261, USA. esejdic@ieee.org.
authors.forename: Ervin
authors.initials: E
authors.lastname: Sejdić
mesh_terms: D061725:Accelerometry; D000465:Algorithms; D001314:Auscultation / Q000379:methods*; D002574:Cervical Vertebrae; D003679:Deglutition; D003680:Deglutition Disorders / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007830:Larynx / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011015:Pneumonia, Aspiration / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D014732:Vibration