SIMULTANEOUS ORAL-NASAL AIR FLOW MEASUREMENTS AND CINEFLUOROGRAPHIC OBSERVATIONS DURING SPEECH PRODUCTION.

The function of the velopharyngeal mechanism has been studied by many investigators using a variety of observational techniques. These methods of observation may be divided into two general categories: a) direct techniques, such as cinefluorographic observations (2, 4, 18, 19, 20), which allow the experimenter to make relatively direct observations of the articulatory mechanism, and b) indirect techniques, such as the measurement of oral and nasal air pressures and flows (1, 3, 5, 11, 14, 15, 17, 21, 28, 24, 26, 27), that provide information from which the investigator can infer articulatory activities. Examination of studies in which these techniques have been used suggests the following conclusions: a) There appears to be little, if any, empirical information concerning relationships between articulatory activities and measures of air flows or pressures. b) There appears to be little definitive information concerning the air flow or pressure characteristics of normal speech and the factors which bring about changes in such characteristics. c) The nasal and oral portions of the vocal tract must be considered together, since it has been shown that they produce interacting effects (7). Due to such interaction, nasal pressures and flows undoubtedly are related to various oral phenomena as well as to the activities of the velopharyngeal mechanism. d) Many of the techniques used to measure air flows and pressures during speech (for example, plugging the nostrils to create a closed system, placing tubes in the mouth, placing a face mask on the subject) place restrictions of varying, but unknown, degrees on the speech mechanism. In view of the above conclusions, it is apparent that a technique designed to measure simultaneous oral and nasal air flows in conjunction