Phonemic Analysis of Consonants in Helium Speech
Russell L. Sergeant · The Journal of the Acoustical Society of America · 1967
A phonemic-confusion matrix for speech in a helium atmosphere was constructed for use in predicting intelligibilities of specially constructed vocabularies for such environments. There is a marked similarity between helium speech and speech in air when intelligibility according to linguistic classification is observed. However, unaccountable differences do exist between the two breathing media for ranked intelligibilities of specific consonants.