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Hearing thresholds during Gz acceleration with masking noise.
Patrick M B Sandor1, Lionel Pellieux, Martine Godfroy
1Département sciences cognitives, Institut de médecine aérospatiale du service de santé des armées (IMASSA), Brétigny sur Orge, France. pmb_sandor@imassa.fr
Aviation, Space, and Environmental Medicine
|November 24, 2004
Summary
Pilot hearing thresholds at 1000 Hz slightly improved under high acceleration (+4 Gz), contrary to expectations. This suggests complex auditory signals can be used in future fighter aircraft human-machine interfaces during G-force exposure.
Area of Science:
- Aerospace Medicine
- Human-Machine Interface Design
- Auditory Perception
Background:
- Future fighter aircraft will integrate 3D sound for human-machine interfaces.
- High acceleration (+Gz) may reduce cerebral blood flow, potentially impairing pilot auditory perception.
- The study investigated the impact of +Gz exposure on hearing thresholds.
Purpose of the Study:
- To test the hypothesis that +Gz exposure raises hearing thresholds due to cochlear vascular deprivation.
- To evaluate the effect of +Gz on auditory perception at specific frequencies.
- To determine the feasibility of using complex auditory cues in high-G environments.
Main Methods:
- Hearing thresholds for pure tones (250, 1000, 6000, 10,000 Hz) were compared at +1 Gz and +4 Gz.
- Steady noise was used to mask centrifuge noise during experiments.
- Participants were exposed to different levels of sustained acceleration.
Main Results:
- Hearing thresholds at 1000 Hz significantly decreased at +4 Gz (47 dB) compared to +1 Gz (53 dB).
- Hearing thresholds remained unchanged at 250, 6000, and 10,000 Hz.
- A paradoxical improvement in hearing at 1000 Hz was observed.
Conclusions:
- The hypothesis of increased hearing thresholds due to +Gz was contradicted.
- The 1000 Hz change is likely due to middle ear transmission disturbances, not central auditory effects.
- The absence of general hearing loss supports the use of 3D sound in aviation interfaces during acceleration.