The Effect of Prolonged Mild Anoxia on Speech Intelligibility

• 成果类型: Article
• 署名作者: Smith, G. M.
• 刊物名称: JOURNAL OF APPLIED PSYCHOLOGY
• ISSN/ISSBN: 0021-9010
• DOI: 10.1037/h0055452
• 发表日期: 1946
• 页码: 255-264

摘要

Using the method and materials described in earlier work with C. P. Seitz (same Jour. 30(2): 1946), 12 subjects were tested for their ability to perceive speech sounds at 4 intervals during an 8-hr. exposure to mild anoxia in a nitrogen dilution chamber at simulated altitude of 10,000 ft. These subjects listened to recorded speech sounds played at a low level of intensity, and checked off the stimulus words on 4 separate tests containing check rows for 11 vowels and 24 conso1nants. The testing periods in the chamber came at 3/4 hr., 21/4 hrs., 43/4 hrs., and 63/4 hrs., respectively. A high protein standardized lunch intervened between the 2d and 3d testing periods, beginning at 33/4 hrs. and lasting 1/2 hr. A control run at 1,810 ft. for 8 hrs. was given under exactly the same conditions which included the wearing of oxygen masks, ear phones, etc., so that the subjects were not aware of altitude differences. The decrement in speech intelligibility was unreliable at the 3/4 hr. period; nearly reliable at 21/4 hrs. and 43/4 hrs.; and unreliable at 63/4 hrs. at which time a marked end spurt in superior performance occurred. This ability to overcome the mild deterioration exhibited in the middle of the run was probably due in part to earlier wandering of attention and boredom. There were subjective reports of greater sleepiness during altitude than during control runs. But there was also clear evidence of a reliable and progressive enlargement of the angioscotoma during the prolonged exposure period. While it seems improbable that significant losses in speech intelligibility will occur on bomber missions at this order of altitude, the subjective factors mentioned may cause errors in speech perception.