Sustained Vowel Production Research Articles

Effects of physiological aging on selected acoustic characteristics of voice.

The relationship between age-related changes in body physiology and certain acoustic characteristics of voice was studied in a sample of 48 men representing three chronological age groupings (25-35, 45-55, and 65-75) and two levels of physical condition (good and poor). A fundamental frequency analysis program (SEARP) was used to measure mean fundamental frequency, jitter, shimmer, and phonation range from samples of connected speech and sustained vowel production. Subjects in good physical condition produced maximum duration vowel phonation with significantly less jitter and shimmer and had larger phonation ranges than did subjects of similar chronological ages who were in poor physical condition. These differences were most apparent in the productions of the elderly subjects. While chronological aging is undoubtedly a contributor to such changes in the acoustic characteristics of voice, these results suggest that age-related changes in body physiology, or physiological aging, also must be considered.

Frequency variability in the aged voice.

Fundamental frequency variations were examined in readings of the fourth and fifth sentences of the "Rainbow Passage" and in the sustained vowel /a/ produced by 20 young adults and 20 older adults. The Tektronix Visipitch provided the fundamental frequency contour (frequency variations in continuous reading) and Honeywell Visicorder determined frequency perturbation in the sustained vowel. Results showed that older speakers produced lower pitches, larger intonational ranges, and greater numbers of inflections in reading than did younger speakers. The maximum change in inflection produced by older adults was significantly greater than that of young adults. In addition, frequency perturbation found in the sustained vowel production of older speakers was significantly greater than that of younger speakers. Information concerning the perceived pitch characteristics of the voices was also obtained. Implications of these findings for the effects of aging on voice as well as diagnosis of laryngeal dysfunction were discussed.

A New Technique for Measuring Velopharyngeal Orifice Area during Sustained Vowel Production: An Application of Aerodynamic Forced Oscillation Principles

A new technique for measuring velopharyngeal orifice area during sustained vowel production is described. The technique is based on a simple oscillatory flow balancing procedure between two aerodynamic branches, a mechanical model of the human upper airway and the subject's upper airway. The area of the velopharyngeal orifice in the model is adjusted until identical oscillatory flows traverse it and the subject's velopharyngeal orifice in response to a common forced oscillatory pressure. When identical oscillatory flows are observed, the area of the adjusted orifice is taken as a measure of the area of the subject's velopharyngeal orifice.

Effects of vowel identity and fundamental frequency on the relationships of vocal intensity to physiological parameters associated with production of sustained vowels

The relationships of subglottal air pressure, airflow rate, glottal resistance, and physiological work to the SPL of vowels produced at three different pitch levels were investigated. The vowels /a/ and /i/ were produced at pitch levels corresponding to the 25%, 50%, and 75% points of the subjects' pitch ranges; the highest pitch level was in the falsetto register for all subjects. At each pitch level, the slopes of the functions relating SPL to the physiological parameters were greater for /a/ than for /i/. The magnitudes of the physiological parameters for /i/ were greater than those for /a/ at the two lower pitch levels, but there was little difference between the vowels at the high pitch level. The magnitudes of the physiological parameters tended to increase for /a/ as pitch level increased, but tended to decrease for /i/ as pitch level increased. The intervowel differences observed at a given pitch level probably are associated with differences in the relative sizes of the oral cavity for the vowels. Intravowel differences between pitch levels can be accounted for by differences in the acoustic coupling between the glottal generator and the oral cavity, particularly at frequencies near the first formant.

Resonant Frequencies and Damping Constants of Resonators Involved in the Production of Sustained Vowels “O” and “Ah”

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