Thomas J. Hixon

Vocalization and breathing during the first year of life

Vocalization and breathing were studied in 40 healthy infants, including five boys and five girls each at ages 5 weeks, 2.5 months, 6.5 months, and 12 months. Breathing was monitored through the use of a variable inductance plethysmograph that enabled estimates of the volume changes of the rib cage, abdomen, and lung, as well as estimates of selected temporal features of the breathing cycle. Four vocalization types were studied intensively. These included cries, whimpers, grunts, and syllable utterances. Breathing behavior was highly variable across the four vocalization types, demonstrating the degrees of freedom of performance available to the infant to accomplish the aeromechanical drive required. Such behavior was influenced by body length, body position, and age, but not by vocalization type and sex. The protocol established is a useful tool for observing the natural course of the emergence of vocalization and breathing during the first year of life.

Influence of Forced Transglottal Pressure Changes on Vocal Fundamental Frequency

Forced transglottal pressure changes (ΔPt) were produced in 10 subjects while they sustained vowels and uttered monosyllables. Pressure changes were applied sinusoidally at both the body surface (subglottally) and the airway opening (supraglottally) by loudspeakers driven at 4–6 Hz (the empirically determined resonant frequency of each subject). Vocal fundamental frequency (f0) was recorded with a throat microphone and analyzed from narrow‐band spectrograms. Results showed values for (Δf0/ΔPt) to be dependent upon vocal frequency, intensity, and register, and to be independent of vowel, voice quality, utterance type (i.e., sustained vowels versus vowels in syllables), and mode of applying pressure. Except for falsetto phonations, (Δf0/ΔPt) values exceeded 5 Hz/cm H2O in only one subject and in the speech range of f0 they were typically 2–4 Hz/cm H2O. These findings fail to support earlier work (Lieberman et al., 1969) based on one of the subjects included here. We conclude that f0 changes characteristic o...

Respiratory kinematics in female classical singers

Summary Kinematic behavior of the respiratory apparatus was studied during speaking and singing in four female subjects, all classical singers. Results revealed that respiratory events were similar to those observed previously for male classical singers. Findings suggest that respiratory function in classical singing is not sex-related in its kinematic manifestations.

Abdominal muscle activity during classical singing

Summary Electromyography was used to investigate abdominal muscle activity during singing in four subjects, all of whom were trained classical singers. Results revealed regional differences in abdominal activation during the expiratory side of the breathing cycle. These were characterized by high-amplitude activity in the lateral region and low-amplitude activity in the middle region. For three subjects, amplitudes were higher in the lower lateral portion of the abdomen than the upper lateral portion. For the remaining subject, amplitudes were higher in the upper lateral portion than the lower lateral portion. Brief decrements in lateral abdominal activity often occurred in association with the onset of the inspiratory side of the breathing cycle. Findings support the concept that the abdomen plays an important role in the posturing of the chest wall for singing.

Vocalization and breathing during the second and third years of life

Vocalization and breathing were studied in 40 healthy young children, including 5 boys and 5 girls at each, of ages of 18, 24, 30, and 36 months. A variable inductance plethysmograph was used to obtain estimates of volume changes of the rib cage, abdomen, and lung, as well as estimates of selected temporal features of the breathing cycle. Results indicated that breathing behavior was influenced by height and age, but not by vocalization type or sex. Such behavior was found to be highly variable, demonstrating that these young children had multiple degrees of freedom of performance available to accomplish the aeromechanical drive required.

Velopharyngeal Function During Vocalization in Infants

Objective: To determine the age at which infants achieve velopharyngeal closure during vocalization. Design: Longitudinal with repeated measures. Setting: Laboratory. Participants: Six healthy infants were studied monthly from ages 2 to 6 months while they interacted with a parent and an investigator. Main Outcome Measures: The presence or absence of velopharyngeal closure, as determined by sensing ram pressure at the anterior nares. Results: The velopharynx was open for windups, whimpers, and laughs, and it was closed for cries, screams, and raspberries, regardless of age. The frequency with which the velopharynx closed during syllable utterances increased significantly with age. Conclusions: Velopharyngeal closure for speech-like utterance increases with age, but is not complete and is still undergoing development at 6 months of age. Velopharyngeal closure during infancy may be influenced by pressure demands of the utterance; however, support for this speculation is stronger for other types of utterances than it is for speech-like utterances. The method used in this study holds promise for evaluating infants with suspected velopharyngeal impairment.

Relative volume changes of the rib cage and abdomen during prephonatory chest wall posturing

Summary This study attempted to shed further light on the nature of prephonatory chest wall posturing by means of an investigation of the relative volume changes of the rib cage and abdomen during such posturing in normal young adult men and women. A new form of relative-volume chart was devised that enabled graphic display of the data in terms of selected ranges of relative volume contributions of the rib cage and abdomen. Choice of these ranges, reflected as contiguous segments on the devised chart, was based on differences in functional significance among them. On the basis of the results obtained, it was concluded that prephonatory chest wall posturing is a behavior that varies within and among subjects and is characterized by a wide range of relative volume contributions of the rib cage and abdomen

Physical Examination of the Abdominal Wall by the Speech-Language Pathologist

A protocol is presented for use by the speech-language pathologist in conducting a physical examination of the abdominal wall. Structural and performance observations are used to reveal the nature ...

Physical Examination of the Diaphragm by the Speech-Language Pathologist

A protocol is presented for use by the speech-language pathologist in conducting a physical examination of the diaphragm. Five clusters of performance activities are used to reveal the nature and d...

Physical Examination of the Rib Cage Wall by the Speech-Language Pathologist

A protocol is offered for use by the speech-language pathologist in conducting a physical examination of the rib cage wall. Structural and performance observations are used to reveal possible rib c...