The Intelligibility of Hydrogen-Speech at 200 Feet of Seawater Equivalent
Medical research progress rept. no. 9
NAVAL SUBMARINE MEDICAL RESEARCH LAB GROTON CT
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The purpose of this study was to evaluate the effect of breathing hydrogen on the intelligibility of speech. Taped recordings were made of a talker breathing normal air within 1 atmospheric pressure absolute ATA and also breathing hydrogen, helium and air at 7 ATA. Responses to the recordings by six panels of listeners were analyzed. As expected, the speech in air at 1 ATA was the most intelligible, and the speech in air at 7 ATA was next best. There was no appreciable difference in mean intelligibility between the helium and hydrogen gas mixtures. These results indicate that any decision in favor of using either hydrogen or helium mixtures in deep sea diving should not depend upon differences in intelligibility of unprocessed helium - versus hydrogen- speech.
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