Deep Sea Diver Speech Distortion-A Chemical-Stress Effect?

Recently linear and nonlinear formant frequency shifting mechanisms have been found to be operating in opposition to each other, on the frequency shift of the formants of a divers speech. These shifts cause speech distortion and are usually solely attributed to the depth of the ocean for a given gas mix. Heliox mix consisting of 79.32% Helium and 20.68% Oxygen was used to record voice of a diver in a hyperbaric chamber during inhalation and exhalation periods. The results were compared with chemical, and physiological stress results to conclude that there may exist physiological stress effects mixed with that of the chemical stress due to the gas mix in addition to the depth and non-air breathing gas. Apparently these have not been separated in the diver speech distortion studies so far, and an attempt is made to correlate these is made in this paper.