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Effect of hypobaric hypoxia on auditory sensitivity
Ken I McAnally1, Dougal B Watson, Russell L Martin
1Air Operations Division, Defence Science and Technology Organisation, Melbourne, Victoria, Australia. ken.mcanally@dsto.defence.gov.au
Aviation, Space, and Environmental Medicine
|December 25, 2003
Summary
Hypobaric hypoxia caused a small reduction in auditory sensitivity at 3700 meters. This 2.57 dB decrease in hearing is unlikely to significantly impact communication effectiveness.
Area of Science:
- Auditory Neuroscience
- Aerospace Medicine
- Human Physiology
Background:
- Previous research on hypobaric hypoxia and hearing is limited by ambient pressure considerations.
- Auditory sensitivity studies require careful control of stimulus levels relative to ambient pressure.
Purpose of the Study:
- To compare auditory sensitivity under hypoxic and normoxic conditions at a simulated altitude of 3700 m.
- To isolate the effects of hypoxia on hearing, controlling for other barometric pressure effects.
Main Methods:
- Auditory sensitivity to 1, 8, 12, and 16 kHz tones was tested.
- Hypoxic condition: inspired oxygen decreased with altitude.
- Normoxic condition: inspired oxygen maintained at sea level equivalent, controlling for barometric pressure effects.
Main Results:
- A mean reduction in auditory sensitivity of 2.57 dB was observed across tested frequencies.
- This reduction occurred under simulated altitude conditions.
Conclusions:
- The observed reduction in auditory sensitivity due to hypobaric hypoxia is minimal.
- This level of hearing change is not expected to significantly impair auditory information transfer.