Vertical excursions allow divers in seafloor habitats to work at depths deeper than thehabitat.Descending excursions from saturation in nitrox have almost all used air as the breathing gas;depth is effectively restric...Vertical excursions allow divers in seafloor habitats to work at depths deeper than thehabitat.Descending excursions from saturation in nitrox have almost all used air as the breathing gas;depth is effectively restricted to less than 60 msw by narcosis and oxygenexposure.The objective is to investigate use of helium mixtures for excursions, taking展开更多
Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of bearing, earache daring compression. Ex...Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of bearing, earache daring compression. Examination showed that the threshold of tower frequency range of hearing was elevated because of the masking effect of the noise in the hyperbaric chamber. Changes in waveform and latency of brainstem evoked response were due to changes in sound wave transmission affected by the chamber pressure and a poor ratio of signal to noise in the hyperbaric environment with heliox. All these changes were transient After leaving the chamber, the hearing threshold and brainstem evoked response returned to normal. Besides, there were no changes in tympanogram, acoustic compliance and stapedius reflex before and after diving. This indicated the designed speed of compression and decompression in the experiment caused no damage to the divers' acoustic system, and the functions of their Eustachain tubes, middle and inner ears were normal during the diving test展开更多
文摘Vertical excursions allow divers in seafloor habitats to work at depths deeper than thehabitat.Descending excursions from saturation in nitrox have almost all used air as the breathing gas;depth is effectively restricted to less than 60 msw by narcosis and oxygenexposure.The objective is to investigate use of helium mixtures for excursions, taking
文摘Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of bearing, earache daring compression. Examination showed that the threshold of tower frequency range of hearing was elevated because of the masking effect of the noise in the hyperbaric chamber. Changes in waveform and latency of brainstem evoked response were due to changes in sound wave transmission affected by the chamber pressure and a poor ratio of signal to noise in the hyperbaric environment with heliox. All these changes were transient After leaving the chamber, the hearing threshold and brainstem evoked response returned to normal. Besides, there were no changes in tympanogram, acoustic compliance and stapedius reflex before and after diving. This indicated the designed speed of compression and decompression in the experiment caused no damage to the divers' acoustic system, and the functions of their Eustachain tubes, middle and inner ears were normal during the diving test
