Effect of sojourn at altitude of 3,500 m on auditory evoked potential in man

Auditory evoked potentials were studied on 27 male subjects to evaluate the effect of sojourn at high altitude (HA). They were initially studied at Delhi (260 m) for their auditory evoked potentials and were then flown to an altitude of 3,500 m. During their stay at HA the same parameter was tested twice, once on the second day of arrival at HA and another on 21st day of stay. Then they were flown back to sea level (SL) and were retested on the third day of return. The results showed a significant delay in the peak latency of wave I of both the right and left ears on the second day of arrival at HA with a persistent delay in wave V even after 3 days of return to SL. The results suggest that HA stress caused a delay in sensory conduction at the cochlear level during the first week of induction, which was normalised during further stay.