Jeannette D. Hoit

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

SummaryWe 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 testmuscle 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.

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.

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.

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.

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.

Effects of Sequential Swallowing on Drive to Breathe in Young, Healthy Adults

Sequential swallowing is the act of swallowing multiple times, without pausing. Because sequential swallowing requires breath-holding, it seems likely that it could increase the drive to breathe. This study was designed to determine if sequential swallowing is accompanied by an increased drive to breathe in young, healthy adults. We predicted that sequential swallowing would be accompanied by prolonged breath-holding in most cases, and that this would be followed by a recovery phase during which ventilation would increase for a brief period. Results showed that not only did healthy participants increase ventilation after sequential swallowing, they also experienced breathing discomfort (dyspnea) despite the fact that they usually continued to breathe during the swallowing sequence. Given that these effects are observable in young, healthy adults, it seems reasonable to assume that individuals with respiratory and/or neurological compromise would also have an increased drive to breathe during sequential swallowing.

A Simple Technique for Determining Velopharyngeal Status during Speech Production

Clinical evaluation of velopharyngeal function relies heavily on auditory perceptual judgments that can be supported by instrumental examination of the velopharyngeal valve. Many of the current instrumental techniques are difficult to interpret, expensive, and/or unavailable to clinicians. Proposed in this report is a minimally invasive and inexpensive approach to evaluating velopharyngeal function that has been used successfully in our laboratory for several potentially difficult-to-test clients. The technique is an aeromechanical approach that involves the sensing of nasal ram pressure (N-RamP), a local pressure sensed at the anterior nares, using a two-pronged nasal cannula. By monitoring the N-RamP signal, it is possible to determine the status of the velopharyngeal port (open or closed) during speech production. Four case examples are presented to support its clinical value.

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...

Nature and Evaluation of Dyspnea in Speaking and Swallowing

Dyspnea (breathing discomfort) is a serious and pervasive problem that can have a profound impact on quality of life. It can manifest in different qualities (air hunger, physical exertion, chest/lung tightness, and mental concentration, among others) and intensities (barely noticeable to intolerable) and can influence a persons emotional state (causing anxiety, fear, and frustration, among others). Dyspnea can make it difficult to perform daily activities, including speaking and swallowing. In fact, dyspnea can cause people to change the way they speak and swallow in their attempts to relieve their breathing discomfort; in extreme cases, it can even cause people to avoid speaking and eating/drinking. This article provides an overview of dyspnea in general, describes the effects of dyspnea on speaking and swallowing, includes data from two survey studies of speaking-related dyspnea and swallowing-related dyspnea, and outlines suggested protocols for evaluating dyspnea during speaking and swallowing.