Air pressure responses to sudden vocal tract pressure bleeds during production of stop consonants: new evidence of aeromechanical regulation. 2004

David J Zajac, and Mark C Weissler
Craniofacial Center, University of North Carolina, Chapel Hill, NC 27599, USA. david_zajac@dentistry.unc.edu

Two studies were conducted to evaluate short-latency vocal tract air pressure responses to sudden pressure bleeds during production of voiceless bilabial stop consonants. It was hypothesized that the occurrence of respiratory reflexes would be indicated by distinct patterns of responses as a function of bleed magnitude. In Study 1, 19 adults produced syllable trains of "puh" using a mouthpiece coupled to a computer-controlled perturbator. The device randomly created bleed apertures that ranged from 0 to 40 mm2 during production of the 2nd or 4th syllable of an utterance. Although peak oral air pressure dropped in a linear manner across bleed apertures, it averaged 2 to 3 cm H2O at the largest bleed. While slope of oral pressure also decreased in a linear trend, duration of the oral pressure pulse remained relatively constant. The patterns suggest that respiratory reflexes, if present, have little effect on oral air pressure levels. In Study 2, both oral and subglottal air pressure responses were monitored in 2 adults while bleed apertures of 20 and 40 mm2 were randomly created. For 1 participant, peak oral air pressure dropped across bleed apertures, as in Study 1. Subglottal air pressure and slope, however, remained relatively stable. These patterns provide some support for the occurrence of respiratory reflexes to regulate subglottal air pressure. Overall, the studies indicate that the inherent physiologic processes of the respiratory system, which may involve reflexes, and passive aeromechanical resistance of the upper airway are capable of developing oral air pressure in the face of substantial pressure bleeds. Implications for understanding speech production and the characteristics of individuals with velopharyngeal dysfunction are discussed.

UI MeSH Term Description Entries
D010700 Phonetics The science or study of speech sounds and their production, transmission, and reception, and their analysis, classification, and transcription. (Random House Unabridged Dictionary, 2d ed) Speech Sounds,Sound, Speech,Sounds, Speech,Speech Sound
D011312 Pressure A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Pressures
D006470 Hemorrhage Bleeding or escape of blood from a vessel. Bleeding,Hemorrhages
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000293 Adolescent A person 13 to 18 years of age. Adolescence,Youth,Adolescents,Adolescents, Female,Adolescents, Male,Teenagers,Teens,Adolescent, Female,Adolescent, Male,Female Adolescent,Female Adolescents,Male Adolescent,Male Adolescents,Teen,Teenager,Youths
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D000388 Air The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
D001696 Biomechanical Phenomena The properties, processes, and behavior of biological systems under the action of mechanical forces. Biomechanics,Kinematics,Biomechanic Phenomena,Mechanobiological Phenomena,Biomechanic,Biomechanic Phenomenas,Phenomena, Biomechanic,Phenomena, Biomechanical,Phenomena, Mechanobiological,Phenomenas, Biomechanic
D013068 Speech Production Measurement Measurement of parameters of the speech product such as vocal tone, loudness, pitch, voice quality, articulation, resonance, phonation, phonetic structure and prosody. Measurement, Speech Production,Measurements, Speech Production,Production Measurement, Speech,Production Measurements, Speech,Speech Production Measurements
D014681 Velopharyngeal Insufficiency Failure of the SOFT PALATE to reach the posterior pharyngeal wall to close the opening between the oral and nasal cavities. Incomplete velopharyngeal closure is primarily related to surgeries (ADENOIDECTOMY; CLEFT PALATE) or an incompetent PALATOPHARYNGEAL SPHINCTER. It is characterized by hypernasal speech. Palatopharyngeal Incompetence,Inadequate Velopharyngeal Closure,Velopharyngeal Incompetence,Incompetence, Palatopharyngeal,Incompetence, Velopharyngeal,Insufficiency, Velopharyngeal,Velopharyngeal Closures, Inadequate

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