An excised hemilarynx setup was developed. The phonatory characteristics of nine excised canine larynges were examined. The left vocal fold of each larynx was then removed and substituted with a vertical plexiglass plate. The larynges were phonated again. Recordings were made of phonation threshold pressure, sound pressure level, average glottal flow, fundamental frequency, and amplitude of vocal fold vibration as observed with a video stroboscope. Measurements were made over a range of subglottal pressures. For the hemilarynx, simultaneous recordings of intraglottal pressure and vocal fold contact area were also made. It was found that amplitude and frequency of vocal fold vibration of the hemilarynx, as well as rates of change of amplitude and frequency as a function of subglottal pressure, were similar to those of the full larynx. Also similar were phonation threshold pressures and ranges of subglottal pressure over which the larynges phonated. The average airflow of the hemilarynx was approximately half that of the full larynx, and the sound pressure level, under similar conditions, was one fourth (about 6 dB less) in the hemilarynx.

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The addition of a fourth type of voice to Titze's voice classification scheme is proposed. This fourth voice type is characterized by primarily stochastic noise behavior and is therefore unsuitable for both perturbation and correlation dimension analysis. Forty voice samples were classified into the proposed four types using narrowband spectrograms. Acoustic, perceptual, and correlation dimension analyses were completed for all voice samples. Perturbation measures tended to increase with voice type. Based on reliability cutoffs, the type 1 and type 2 voices were considered suitable for perturbation analysis. Measures of unreliability were higher for type 3 and 4 voices. Correlation dimension analyses increased significantly with signal type as indicated by a one-way analysis of variance. Notably, correlation dimension analysis could not quantify the type 4 voices. The proposed fourth voice type represents a subset of voices dominated by noise behavior. Current measures capable of evaluating type 4 voices provide only qualitative data ͑spectrograms, perceptual analysis, and an infinite correlation dimension͒. Type 4 voices are highly complex and the development of objective measures capable of analyzing these voices remains a topic of future investigation.

Objective To determine the effect of bolus volume on pharyngeal swallowing using high resolution manometry (HRM). Study design Repeated measures with subjects serving as own controls. Methods Twelve subjects swallowed four bolus volumes in the neutral head position: saliva; 5 ml water; 10 ml water; and 20 ml water. Pressure measurements were taken along the length of the pharynx using a high resolution manometer, with emphasis placed on the velopharynx, tongue base, and upper esophageal sphincter (UES). Variables were analyzed across bolus volumes using three-way repeated measures analysis of co-variance (ANCOVA) investigating the effect of sex, bolus volume, and pharynx length. Pearson’s product moment tests were performed to evaluate how pharyngeal pressure and timing events changed across bolus volume. Results Velopharyngeal duration, maximum tongue base pressure, tongue base pressure rise rate, UES opening duration, and total swallow duration varied significantly across bolus volume. Sex did not have an effect, while pharynx length appeared to affect tongue base pressure duration. Maximum velopharyngeal pressure and minimum UES pressure had a direct relationship with bolus volume, while maximum tongue base pressure had an inverse relationship. Velopharyngeal pressure duration, UES opening duration, and total swallow duration increased as bolus volume increased. Conclusions Differences in pharyngeal pressures and timing of key pressure events were detected across varying bolus volumes. Knowing the relationships between bolus volume and pharyngeal pressure activity can be valuable when diagnosing and treating dysphagic patients. Level of evidence N/A.