Intraoral air pressure discrimination under conditions of partial and complete resistance.

This study assessed a sample of normal-speaking individuals' ability to discriminate differences in their self-generated intraoral air pressures. Two conditions were employed: (1) open tube in which subjects had to sustain an expiratory breath stream to maintain the target pressure, and (2) closed tube in which there was complete resistance to the subjects' breath stream. Analysis of variance revealed no significant difference (p > 0.05) in subjects' ability to discriminate differences in their self-generated intraoral air pressure as a function of open or closed tube conditions. However, subjects' discrimination scores significantly increased (p < 0.05) as the standard pressure was increased.

Respiratory and laryngeal function associated with experimental coupling of the oral and nasal cavities.

Three experimental openings (10 mm2, 20 mm2, 30 mm2) were placed one at a time in a man's palatal obturator at a location approximating the junction of the prepalate and the palatal shelves. The man's laryngeal and respiratory function were examined during his production of a series of CV syllables [pa] repeated at a comfortable and loud vocal intensity for each of the three experimental conditions. Two more conditions, in which the subject's obturator was not altered (no hole) and in which no obturator was worn, were also included for study. Laryngeal and respiratory function adjustments were most apparent during the 30 mm2 hole size and no obturator conditions. Laryngeal adjustment, as measured by fundamental frequency, was the most identifiable. A respiratory adjustment, which involved the expenditure of more lung volume as nasal airflow leakage increased, was also observed. These observations imply an active physiologic adjustment rather than a passive response to aberrant oronasal coupling.

Level of accuracy and degree of precision in attempting to maintain steady levels of biting force.

The primary purpose of this study was to assess the level of accuracy (bias) and degree of precision for a group of 24 normal subjects attempting to maintain a constant biting force at levels of 100 gm, 500 gm, 1000 gm and 2000 gm for a period of 10 s each. Accuracy is defined as the difference between subjects' actual level of biting force and the target value they were trying to achieve. Precision is the level or range of variability demonstrated by the subjects while attempting to bite with a constant level of force. Subjects' performance relative to accuracy and precision was also compared when using the central incisors vs. the first permanent molars. Assessment of bite force was measured using a specially designed strain gauge scale which permitted subjects to visually monitor when their biting force equalled a preset resistance. Each subject was instructed to bite on the end of a plastic sheathed steel beam with enough force to activate the indicator needle on the voltage meter to its central position and to try to maintain a constant level of biting force (by attempting to keep the indicator needle steady in its central position). No significant (P > 0.05) differences were found in mean accuracy in bite force for gender or specific teeth used in the biting task. However, a significant difference (P < 0.0001) in mean accuracy in bite force was found to exist between the target levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Human pinch-force discrimination.

Pinch-sustaining tasks such as holding a pencil, fork, or key require the exertion of different levels of force. There is little information concerning normal subjects' ability to discriminate differences in their pinching force, so the purpose of this study was to evaluate the ability of 24 normal young women to discriminate differences in their self-generated isometric tip and lateral pinching force. Resistance forces of 10, 25, 50, and 75% of known normal maximum pinching force were selected as standards. Subjects were presented a series of paired resistance settings of which the first resistance in each pair was the standard and the second resistance a comparator of some greater amount. This procedure of paired comparisons was continued until subjects' threshold of discrimination between two pinching forces was established. The results indicated that subjects' pinch-force discrimination at the standard of 50% of reported maximum pinching force was significantly better for the tip condition than for the lateral condition. This study has described an instrumentation and the methodology for assessing individuals' ability to discriminate differences in their pinching force at submaximal levels.