High-Speed Image Analysis Comparing Loading of Vocal Folds During Coughing and Phonation: A Case Study

Coughing is related to voice problems, since it involves firm glottal closure, fast glottal opening, and high subglottic pressure and flow rate. In this study, the glottal area variation and movements of laryngeal structures during coughing and phonation are compared.

High-speed laryngoscopy recordings were made of a normophonic male participant with a healthy larynx producing a neutral vowel and coughing. Oral air pressure was registered in a mouthpiece, through which an endoscope was inserted into the pharynx. Electroglottography, acoustic, and pressure signals were recorded simultaneously. The glottal width variation at the membranous and cartilaginous parts of the glottis was derived from the high-speed images, and the strong vibration of the false vocal folds was also registered.

In coughing, compared to ordinary vowel phonation in nearly the same sound pressure level (93-94 dB_6cm), the glottal width was 25% larger at the middle of the vocal folds, the maximum glottal opening velocity was 39% higher, and the maximum glottal width declination rate during glottal closing was up to three times higher. The maximum acceleration was 40% higher, and the maximum deceleration was 47% higher. Fundamental frequency f₀ was the highest (ca. 400 Hz) at the beginning of the first phase of a typical coughing process. During the last part of the coughing process, f₀ decreased from ca. 250 Hz to ca. 85 Hz at the phonation offset.

The remarkable increase in maximum glottal width declination rate implies much higher vocal fold loading in coughing compared to phonation.