RESPIRATORY TRANSITION BETWEEN QUIET AND SPEECH BREATHING AND ITS TIMING RELATIONSHIP TO PHONATORY INITIATION

PAUL ALAN COOKE, Purdue University

Abstract

The purpose of this investigation was to examine the respiratory transition from quiet breathing to speech breathing during sentence productions and a vocal reaction time task. The lung volume changes were sensed by strain gauge impedance pneumographs (IP) that were attached around the thorax and abdomen. A small laboratory computer (PDP 8/L) monitored the thoracic IP signals; triggered an auditory cue at 20%, 50%, or 80% level of quiet inspirations and expirations; and calculated and printed end-inspiratory levels, end-expiratory levels, durations, and average air flow rates of the respiratory cycles. Five adult males served as subjects. Each subject was instructed to identify the trial number and the subject number upon the first auditory cue and to phonate /a/ as fast as possible upon the second auditory cue. A total of 24 pairs of the sentence /a/ productions were made in each of seven experimental sessions. The thoracic and abdominal IP signals, and voice signals were recorded on a multichannel FM tape recorder. The respiratory patterns and reaction times were subsequently derived from oscillographic tracings of these recorded signals. Results of the present investigations showed that in the sentence task, the most prevalent respiratory maneuvers were characterized by a higher lung volume level prior to speech expiration. When cued during inspiration, 80% of the time the subjects' inspiration simply continued to a higher end-inspiratory level before phonation. The remaining 20% of the time, there was a slight pause or a short expiration, followed by an inspiration to the higher lung volume level. When cued during expiration, about 80% of the time, the quiet expiration was short-circuited (short and shallow expiration), and a deeper inspiration followed prior to speech. In the remaining 20% of the time, the speech was initiated within the cued expiration. Regardless of the pattern used, resting expiratory level was rarely achieved in the transitional respiratory cycles. With the particular sentence task, therefore, pre-speech tuning of the respiratory mechanism appears to take advantage of the high lung volume level, i.e., greater air supply and elastic recoil force, in meeting the aerodynamic requirements for speech. In addition, there appears to be some self-imposed time constraint because all respiratory modifications were initiated within the cued respiratory cycle. The respiratory-phonatory interaction during the vocal RT task revealed that prompting subjects from high-, medium- and low lung volume levels during tidal breathing did not systematically influence the total reaction time. However, expiratory-cued samples were on the average faster than inspiratory-cued trials. For two of the five subjects, such differences exceeded 15 msec, which were statistically significant. In addition, all five subjects demonstrated a significant reduction in vocal reaction times across the seven experimental sessions. Despite a 48-trial practice session, the subjects decreased their average times 40-55 msec throughout the experiment. The RT data support the contention that respiratory phasal triggering can produce statistical differences, but other factors like the level of alertness, motivation, and the practice effect may overshadow physiological/aerodynamic differences. Respiratory strategies to initiate the fast vocalization were highly idiosyncratic. Although five basic patterns were employed by the subjects, the most frequently used pattern was an oppositional respiratory movement, whereby the abdomen moved sharply inward while the thorax was moving outward. In addition, regardless of the pattern used, the abdominal movement occurred about 40 msec before the thoracic movement. The respiratory data support the contention that the abdominal-diaphragmatic unit plays the most prominent role in initiating the pre-speech respiratory posture before fast vocalizations.

Degree

Ph.D.

Subject Area

Communication

COinS