Effect of normobaric hypoxia on auditory sensitivity

Previous psychophysical studies of hypoxia's effects on auditory sensitivit y have provided mixed results but the weight of evidence supports the concl usion that sensitivity is unaffected by hypoxia. This conclusion is discrep ant with that drawn from physiological studies in which hypoxia has been fo und to affect auditory-evoked response (AER) latency. One possible explanat ion of this discrepancy concerns the relatively low maximum frequency (8 kH z) for which hypoxia's effects were assessed in the psychophysical studies. We have extended the range of frequencies over which hypoxia's effects hav e been examined to include frequencies up to 16 kHz. Thresholds for 1-, 8-, 10-, 12-, 14- and 16-kHz tones were measured at levels of hypoxia equivale nt to altitudes of 0, 1200, 2400 and 3700 m. Our results indicate that sens itivity for frequencies up to 16 kHz is unaffected by hypoxia. We suggest t hat AER latency does not provide a valid measure of auditory sensitivity.