Accession Number : AD0669089

Title :   SPEECH IN AN ARTIFICIAL ATMOSPHERE (30% HELIUM-70% OXYGEN).

Descriptive Note : Final rept. Oct 65-May 67,

Corporate Author : DAYTON UNIV OHIO RESEARCH INST

Personal Author(s) : Nixon,Charles W. ; Mabson,William E. ; Trimboli,Frank ; Welch,B. E.

Report Date : DEC 1967

Pagination or Media Count : 38

Abstract : During a simulated space mission, speech was analyzed to investigate the effects on communication of a 56-day exposure to a cabin atmosphere composed of 30% helium and 70% oxygen at an altitude of 27,000 feet. Results of physical and subjective analyses indicated: (1) Word intelligibility was satisfactory so long as the level of ambient noise in the speech frequency range did not exceed the speech level. (2) Fundamental frequency remained relatively unaffected by the 30% helium-70% oxygen gas mixture. (3) Mean second and third formant frequencies were 1.109 and 1.079 times higher in the helium exposure than in the initial ground level condition. (4) There was no adaptation in formant frequency shift as a function of time in the helium mixture, however, some persistency effects were seen during the post-exposure condition. (5) Calculated velocity of sound ratios were found to overestimate the measured amount of formant shift by a mean factor of 0.05 for the 30% helium mixture. (6) Speech quality was judged to deteriorate with increased duration of exposure to the 30% helium mixture. Comparisons were made between these findings and the results of a previous study which investigated speech produced in a 56% helium-44% oxygen atmospheric mixture. (Author)

Descriptors :   (*SPACE COMMUNICATIONS, SPEECH), (*SPEECH, INTELLIGIBILITY), SPACE FLIGHT, SIMULATION, HELIUM, OXYGEN, NOISE, SPEECH RECOGNITION

Subject Categories : Voice Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE