Influence of continuous speaking on ventilation.

This study was conducted to explore the influence of speaking on ventilation. Twenty healthy young men were studied during periods of quiet breathing and prolonged speaking using noninvasive methods to measure chest wall surface motions and expired gas composition. Results indicated that all subjects ventilated more during speaking than during quiet breathing, usually by augmenting both tidal volume and breathing frequency. Ventilation did not change across repeated speaking trials. Quiet breathing was altered from its usual behavior following speaking, often for several minutes. Speaking-related increases in ventilation were found to be strongly correlated with lung volume expenditures per syllable. These findings have clinical implications for the respiratory care practitioner and the speech-language pathologist.

Competition between gas exchange and speech production in ventilated subjects.

Competition between airflow requirements for speaking and gas exchange occurs in ventilator-dependent tracheotomized subjects who can 'steal' air from alveolar ventilation during the ventilator's inflation phase to produce sound. We wondered whether these subjects adopted strategies to minimize hypoventilation when speaking, particularly when ventilatory drive and respiratory discomfort are increased by hypercapnia. We recorded speech and ventilatory and speaking volumes in five ventilated subjects during reading and extemporaneous speech. All subjects spoke during the ventilator's inflation (and expiratory) phase, losing approximately 15% of their inspired tidal volume. During induced hypercapnia (15 mmHg increase in PetCO2) which caused shortness of breath, all subjects could still speak adequately. Two subjects 'adapted' to hypercapnia by reducing the air used for speaking during inflation. In contrast, one subject reacted, as normal subjects do, by increasing the airflow per syllable (a mal-adaptive strategy in ventilated subjects). These changes were modest despite the strong hypercapnic stimulus.

Respiratory function during speaking and singing in professional country singers.

Respiratory function during speaking and singing was investigated in six male professional country singers. Function was studied using magnetometers to transduce anteroposterior diameter changes of the rib cage and abdomen while subjects performed various respiratory maneuvers, speaking activities, and singing activities. Results indicated that respiratory behavior during speaking was generally the same as that of other normal subjects. Respiratory behavior during singing resembled that of speaking. Discussion includes comparison of respiratory performance of present singers with untrained singers and classically trained singers. Implications are offered regarding how the results might be applied to the prevention of voice disorders by education and training of country singers.

Cognitive-linguistic demands and speech breathing.

This investigation examined the influence of cognitive-linguistic processing demands on speech breathing. Twenty women were studied during performance of two speaking tasks that were designed to differ in cognitive-linguistic planning requirements. Speech breathing was monitored with respiratory magnetometers from which recordings were made of the anteroposterior diameter changes of the rib cage and abdomen. Results indicated that speech breathing was similar across speaking conditions with respect to nearly all measures of lung volume, rib cage volume, and abdomen volume. Task-related differences were found for certain fluency-related measures. Specifically, the number of syllables produced per breath group was smaller, average speaking rate was slower, and average lung volume expended per syllable was greater under a higher cognitive-linguistic demand condition than under a lower-demand condition. These differences were explained by the fact that silent pauses, particularly those associated with expiration, were more prevalent and longer in duration under the higher-demand condition. It appears that the mechanical behavior of the breathing apparatus during speaking generally is unaffected by variations in cognitive-linguistic demands of the type investigated; however, fluency-related breathing behavior appears to be highly sensitive to such demands.

Influence of body position on breathing and its implications for the evaluation and treatment of speech and voice disorders.

This paper examines how breathing differs in the upright and supine body positions. Passive and active forces and associated chest wall motions are described for resting tidal breathing and speech breathing performed in the two positions. Clinical implications are offered regarding evaluation and treatment of breathing behavior in clients with speech and voice disorders.

Age and velopharyngeal function during speech production.

This investigation was designed to determine if velopharyngeal function during speech production, as reflected in measures of nasal air flow, differs with age in adults. Eighty subjects were studied, 40 women and 40 men, representing four age groups (20-30, 40-50, 60-70, and 80 + years). Results showed no age-related differences in nasal air flow. Sex-related differences in flow were found on productions of nasal consonants only. These findings do not support the suggestion of Hutchinson, Robinson, and Nerbonne (1978) that velopharyngeal function deteriorates with age.

Speech production during mechanical ventilation in tracheostomized individuals.

This investigation provides the first detailed description of speech production during mechanical ventilation. Seven adults with tracheostomies served as subjects. Recordings were made of chest wall motions, neck muscle activity, tracheal pressure, air flow at the nose and mouth, estimated blood-gas levels, and the acoustic speech signal during performance of a variety of speech tasks. Results indicated that subjects spoke for short durations that spanned all phases of the ventilator cycle, altered laryngeal opposing pressures in response to the continually changing tracheal pressure wave, and expended relatively small volumes of gas for speech production. Speech was improved by making selected ventilator adjustments. Suggestions for clinical interventions are offered.

Effect of lung volume on voice onset time (VOT).

This investigation was designed to test the hypothesis that voice onset time (VOT) varies as a function of lung volume. Recordings were made of five men as they repeated a phrase containing stressed /pi/ syllables, beginning at total lung capacity and ending at residual volume. VOT was found to be longer at high lung volumes and shorter at low lung volumes in most cases. This finding points out the need to take lung volume into account when using VOT as an index of laryngeal behavior in both healthy individuals and those with speech disorders.

Age and laryngeal airway resistance during vowel production in women.

An investigation was conducted to determine if laryngeal valving economy, as reflected in measures of laryngeal airway resistance during vowel production, differs with age in women. Seventy healthy women were studied, 10 each at age 25, 35, 45, 55, 65, 75, and 85 years. Results indicated that laryngeal airway resistance did not differ significantly with age, although it was noted that the 45-year-old women generally had lower laryngeal airway resistance values. This pattern of function differs from that observed in men (Melcon, Hoit, & Hixon, 1989). Discussion of findings includes consideration of factors that might influence laryngeal function during speech production in women. Clinical implications are offered.

Respiratory and laryngeal function during whispering.

Established procedures for making chest wall kinematic observations (Hoit & Hixon, 1987) and pressure-flow observations (Smitheran & Hixon, 1981) were used to study respiratory and laryngeal function during whispering and speaking in 10 healthy young adults. Results indicate that whispering involves generally lower lung volumes, lower tracheal pressures, higher translaryngeal flows, lower laryngeal airway resistances, and fewer syllables per breath group when compared to speaking. The use of lower lung volumes during whispering than speaking may reflect a means of achieving different tracheal pressure targets. Reductions in the number of syllables produced per breath group may be an adjustment to the high rate of air expenditure accompanying whispering compared to speaking. Performance of the normal subjects studied in this investigation does not resemble that of individuals with speech and voice disorders characterized by low resistive loads.

Speech breathing in individuals with cervical spinal cord injury.

Ten men with cervical spinal cord injury were studied using magnetometers to record surface motions of the chest wall during speech breathing. Individual speech breathing patterns reflected inspiratory and expiratory muscular sparing. Subjects compensated for expiratory muscle impairment by speaking at large lung volumes, presumably to take advantage of the higher recoil pressures available at those volumes. Similarly, subjects used larger lung volumes to increase loudness. Abnormal chest wall behavior was attributed in large part to loss of abdominal muscle function. Because of this, speech breathing in individuals with cervical spinal cord injury may be improved by the use of abdominal binders.

Speech breathing in children and adolescents.

An investigation was conducted to elucidate the nature of speech breathing in children and adolescents and to determine if sex and age influence performance. Eighty healthy boys and girls representing four age groups (7, 10, 13, and 16 years) were studied using helium dilution to obtain measures of subdivisions of the lung volume and using magnetometers to obtain measures of resting tidal breathing and speech breathing. Results for subdivisions of the lung volume and resting tidal breathing revealed sex- and age-related differences, most of which were attributable to differences in breathing apparatus size. Results for speech breathing indicated that sex was not an important variable, but that age was critical in determining speech breathing performance. The most substantial differences were between the 7-year-old group and older groups. These differences were characterized by larger lung volume, rib cage volume, and abdominal volume initiations and terminations for breath groups, larger lung volume excursions per breath group, fewer numbers of syllables per breath group, and larger lung volume expenditures per syllable for the 7-year-old group compared to older groups. In most respects, speech breathing appeared adultlike by the end of the first decade of life. Clinical implications regarding these findings are offered.

Speech breathing in women.

Thirty healthy women representing three age groups (25, 50, and 75 years) were studied with respect to general respiratory function and speech breathing. Certain subdivisions of the lung volume differed with age: vital capacity, expiratory reserve volume, and residual volume. Speech breathing also differed with age and was characterized by differences in lung volume excursion, rib cage volume excursion, lung volume initiation, rib cage volume initiation, and lung volume expended per syllable. Age-related differences in general respiratory function and speech breathing are discussed in relation to possible underlying mechanisms. In addition, patterns of function observed in women are compared to those observed in men in an earlier investigation (Hoit & Hixon, 1987). Clinical implications are drawn regarding the evaluation and management of speech breathing disorders.

Age and laryngeal airway resistance during vowel production.

An investigation was conducted to determine if laryngeal valving economy, as reflected in measures of laryngeal airway resistance during vowel production, varies across adulthood. Sixty healthy men were studied, 10 from each of six age groups--25, 35, 45, 55, 65, and 75 years (+/- 2 years). Results indicated that there are age-related differences in laryngeal airway resistance during vowel production and that these differences are characterized by a lower mean resistance in 75-year-old men than in younger men of the ages studied. This finding provides insight into the impact of age on laryngeal function and has important implications for the evaluation and management of men with voice disorders.

Abdominal muscle activity during speech production.

Abdominal muscle activity was investigated during resting tidal breathing and speech production in upright and supine body positions in five male and five female young adult subjects. Results showed that patterns of abdominal electromyographic (EMG) activity were highly dependent on body position. Data for resting tidal breathing resembled those of previous investigations and revealed one sex-related finding. Data for speech production indicated that the lateral region of the abdomen was highly active in the upright position and occasionally active in the supine position. In the upright position, lateral EMG levels during speech production were characterized by generally higher levels in the lower than upper lateral sites and were almost always higher than during resting tidal breathing. In the supine position, EMG levels during speech production occasionally exceeded those associated with resting tidal breathing but were substantially lower than those associated with upright speech production. Abdominal EMG activity was most prevalent during loud speech production and during speech produced at low lung volumes. Findings are discussed in relation to current knowledge of respiratory mechanics and neural control.

Age and speech breathing.

Thirty healthy men representing three widely different age groups (25, 50, and 75 years) were studied with respect to general respiratory function and speech breathing. Subdivisions of the lung volume were found to differ with age and most markedly so for measures of vital capacity and residual volume. Speech breathing also was found to differ with age and was characterized by differences in lung volume excursion, rib cage volume initiation, number of syllables per breath group, and lung volume expended per syllable. Age-related differences in general respiratory function and speech breathing are discussed in relation to possible underlying mechanisms. In addition, implications are drawn regarding the evaluation and management of individuals with speech breathing disorders.

Body type and speech breathing.

Diameter changes of the rib cage and abdomen were recorded during tidal breathing and speech production in 12 adult male subjects grouped on the basis of prominence on three body type components: relative fatness, relative musculoskeletal development, and relative linearity. Data were charted to solve for lung volume, volume displacements of the rib cage and abdomen, and muscular mechanism. Tidal breathing differed across subject groups with regard to depth, rate, and chest wall configuration. Subjects rated high in relative fatness breathed deeper, slower, and with a greater chest wall deformation from relaxation than did other subjects. Speech breathing differed across subject groups with regard to relative volume contributions of the rib cage and abdomen, abdomen excursions, rib cage paradoxing, and chest wall configuration. Subjects rated high in relative fatness demonstrated substantial abdomen contributions to lung volume change, large abdomen excursions, frequent rib cage paradoxing, and marked chest wall deformations from relaxation. By contrast, subjects rated high in relative linearity demonstrated large rib cage contributions to lung volume change, small abdomen excursions, and slight chest wall deformations from relaxation. Subjects rated high in relative musculoskeletal development generally represented a mixture of characteristics of the other two subject groups in their speech breathing performance. Functional differences are discussed in relation to possible underlying mechanism and inferences are drawn concerning evaluation and management of individuals with speech breathing disorders.

Relative activation of two human elbow flexors under isometric conditions: a cautionary note concerning flexor equivalence.

We examined the electromyographic (EMG) activity of two human elbow-flexor muscles, biceps brachii and brachioradialis, during isometric contractions. The task required subjects to match the EMG level of one of the muscles (the control muscle) to one of four target levels (5, 10, 15, or 20% of maximum) at various elbow angles. A new technique was developed for the target-matching task. The activity of the other muscle (the test muscle) was simultaneously recorded during the task. For the notion of flexor equivalence to be supported, the EMG levels for the two muscles should have covaried. This was not the case. The results revealed three features: (1) while the control-muscle EMG remained constant across joint angles, the test-muscle EMG varied with joint angle, and the trend of this variation differed among subjects; (2) in nine out of ten subjects the trend of test-muscle EMG variation with joint angle was reversed when the other muscle served as the test muscle; and (3) the test-muscle EMG associated with the four target levels was subject-, muscle-, and angle-dependent. These results caution against the generalization of the flexor equivalent concept to isometric conditions. In particular, the activity of one muscle is not a reliable indicator of the activity of other muscles subserving the same joint action.