This study is an extension and a refinement of an earlier study by the same investigators (3). In the earlier study it was demonstrated that an altitude of 18,500 ft., simulated in a nitrogen dilution chamber, produced a statistically reliable decrement in speech intelligibility under certain conditions of initial difficulty. It was pointed out that the magnitude of the decrement, though not large, was indicative of a change that, under trying conditions, could become hazardous in commercial and military aviation. Though it is common practice to use oxygen above 10,000 or 12,000 ft., a pilot flying at 40,000 to 45,000 ft. breathing pure oxygen has, because of the reduced oxygen tension in the lungs, a physiology which roughly corresponds to that of a man flying at 16,000 to 18,000 ft. without oxygen. The demonstration of a decrease in speech intelligibility in this general altitude range is, therefore, not without some practical significance.It was felt that the effect of altitude on speech intelligibility observed in the previous study would have been greater had some more adequate means been found to equate the difficulty of the test materials used in the altitude runs with those used in the control runs. It also seemed desirable to investigate the possibility of a decrement in speech intelligibility at altitudes somewhat lower than 18,500 ft., the altitude selected in the first investigation. The purpose of the present study was to make such an investigation with improved techniques. * The authors are indebted to the Iinde Air Products Co. for a liberal grant of oxygen and nitrogen, and to Messrs. Mortimer Feinberg and Max Rosenbaum for valued clerical and statistical assistance. ' We are indebted to the RCA Manufacturing Co. and to Mr. W. L. Tesch of the record engineering department for their courtesy. 8 Turntable unit model 199 and pick-up model 209. * Model 87B. 5 Type588A.
It is nearly axiomatic that audiovisual (AV) speech is more intelligible than audio-only (A-only) speech, particularly when the speech is presented in a challenging listening environment, such as in background noise [e.g., MacLeod and Summerfield, Br. J. Audiol., 2 (1987)]. No previous research on audiovisual speech perception has examined the perception of children’s speech. Children may elicit a smaller AV benefit than adults, as their visual articulatory movements are more variable than adults’ [e.g., Smith and Goffman, J. Speech Lang. Hear. Res. 41 (1998)], and hence are less informative perceptual cues. Alternatively, the overall lower intelligibility of children’s A-only speech might lead them to elicit overall higher AV benefits than adults. To examine this question, we collected developmentally appropriate sentence productions from five, 4-6 year old children, and five sex-matched adults. Ongoing work is examining the intelligibility of these sentences in multitalker babble in A-only and AV conditions in a variety of signal-to-noise ratios, so that we can compare AV benefits for children and adults when A-only intelligibility is matched. Both sentence intelligibility and eye gaze during perception are being measured. Results will help us understand the role of individual-speaker variation on the magnitude of AV benefit.
Although perception of race is known to influence speech intelligibility, speech has often been studied without careful attention to this variability. It has been common to study language in an audio-only modality, which fails to capture the multimodal natures of language and person perception. We have developed a set of audiovisual study materials consisting of participants producing individual sentences selected from two different sets of standard materials. The corpus we have created is intentionally diverse with respect to racial self-report. However, there is extraordinary diversity in how persons who share a racial identification may present. The complex and variable relationship between physical features and the construction of social status demands that we reject reliance on self-reports when characterizing the diversity of our sample. In two experiments, participants viewed faces and listened to voices of people who contributed to the audiovisual corpus. The results allow us to explicitly characterize how the participants in the corpus may be racialized by observers, independent of their self-report. We argue that examining cognitive processes, which give rise to racialized and gendered perceptions, is foundational to advancing our understanding of speech perception in realistic environments with high degrees of variability in personal appearance and linguistic behavior.
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