Open slope quotient: a new glottographic parameter

Glottographic phase difference in recurrent nerve paralysis

Phase measures with simultaneously recorded electroglottography (EGG) and photoglottography (PGG) signals have been studied in canine models and found to be sensitive to the effect of recurrent laryngeal nerve (RLN) paralysis on vocal fold vibration. This study examined the usefulness of this type of measure in clinical application. The combined glottographic signals were obtained from 5 men with a diagnosis of unilateral RLN paralysis and 5 age-matched controls. In the patient group, EGG waveforms were found to have a consistent phase delay in relation to PGG. A measure of the overall glottographic phase difference (GPD) was found to significantly distinguish the control group (mean GPD = 0.2371 ms) from the patient group (mean GPD = -0.2765 ms). A validity analysis performed on 19 subjects with or without unilateral RLN paralysis confirmed that the GPD test had a relatively high efficiency (91.7%) in detecting unilateral RLN paralysis in the male population.

Estimation of alveolar pressure during speech using direct measures of tracheal pressure

The pressure in the alveoli of the lungs, created by the elastic recoil of the lungs and respiratory muscle activity, is referred to as alveolar pressure (Pa). The extent to which tracheal pressure (Pt) approximates Pa depends on the resistance to airflow offered by structures above and below the point at which tracheal pressure is measured. An understanding of the relationship among Pa, Pt, and upper and lower airway resistance, and how these values fluctuate during speech, could aid in interpretation and modeling of speech aerodynamics. The purpose of this study was to (a) obtain values for lower airway resistance (Rlow), (b) use these Rlow values to estimate Pa during speech, and (c) quantify the degree to which Pt approximates Pa during production of voiced and voiceless sounds, in comparison to inhalation. In addition, the results were discussed in terms of the degree to which the respiratory system functions as a pressure source. Tracheal pressure (obtained with tracheal puncture) and airflow were measured during sentence production in 6 subjects. Using a technique introduced in this paper, Rlow was determined from measures of tracheal pressure and flow obtained during a sudden change in upper airway resistance because of release of a voiceless plosive. Mean Rlow values ranged from 0.14 to 0.32 kPa/(l/s). Each subject's mean Rlow was used to derive a time-varying measure of Pa during speech from continuous measures of tracheal pressure and airflow. Pt was approximately 95% of Pa during phonation (i.e., when the vocal folds were adducted), 75% of Pa during release of the voiceless stop consonant /p/, and 55% of Pa during inhalation (i.e., when the vocal folds were abducted). Therefore, the degree to which the respiratory system functioned as an ideal pressure source varied during speech. The ability to estimate Pa provides a measure of the pressure produced by the respiratory system that is not influenced by laryngeal activity.